By 
Lincoln Spector, 
PCWorld 
How did things get this messed up? Windows has slowed to a crawl. Programs won't run. The 
free firewall you installed last year won't update or uninstall itself.
System Restore hasn't helped; neither have your assorted cleanup and 
antimalware programs. Only one option remains: Reinstall Windows and start from scratch.
I'm not going to lie to you--this is a scary and time-consuming 
job. Your PC may be unusable for a day or more. You could even lose all 
of your data.
  And let's face it: You'd be wise to avoid this chore if at all 
possible. If someone in tech support tells you to do it, get a second 
opinion, and then a third.
  If you have to reinstall--and sometimes it is necessary--here's how to make the process as safe and painless as possible.
  
Gather What You Need
You'll have to collect a few things before you can begin.
  First, you'll need your 
recovery tool. What's that? If 
you're using the version of Windows that came on your PC, it's probably 
in a hidden partition on the computer's hard drive. That partition 
contains the information necessary to restore the hard drive to its 
factory condition.
  Obviously, a hard-drive partition is not something you have to 
gather. But if your PC is a few years old, the recovery tool may be on 
one or more CDs or DVDs instead. Find the discs that came with your PC 
and see if anything looks promising. Alternatively, check the PC's 
manual to learn what kind of recovery tool came with the machine, and, 
if it's on a partition, how to access it.
  If you 
upgraded Windows since you bought the PC--for instance, going from XP or Vista to Windows 7--the upgrade disc is now your recovery tool.
  If you can't find a recovery disc, and the PC has no hidden 
partition (or offers no workable way to access that partition), contact 
the system manufacturer to see what they can do for you. Read "
How Do I Restore Windows If I've Lost My Restore CD?" for details.
  After Windows installs, you'll have to reinstall all of your 
programs. Collect all the original discs or downloaded installation 
files, and all of your license numbers.
  You'll want an empty external hard drive with a capacity at least 
as large as your existing hard drive. Another external hard drive will 
come in handy later. That one doesn't have to be empty; you'll need only
 a part of it.
  Finally, you'll need time. The best-case scenario for a reinstall 
is a day. The worst case: three or four days. You'll be spending a lot 
of that time waiting, so get a good book, too.
  
Back Up Everything
Things could go horribly wrong, so you need to make a backup of 
your entire drive. That way, you can at least return to where you were 
before the reinstall.
  You also have to create a backup of your data, because the reinstall might destroy everything on your hard drive.
To manage both tasks, use cloning software to turn the empty external
 drive into an exact copy of your internal hard drive. I recommend 
EASEUS Todo Backup,
 which performs both image backups and cloning. For this job, I 
recommend the cloning because it will make the later job of restoring 
the data files easier. On the other hand, an image backup doesn't 
require an external drive all to itself (although it will require a 
large piece of one). Either option will work.
Be sure to create an emergency boot disc with EASEUS or whatever 
program you use to do the cloning. Without that, you may not be able to 
recover from a disaster.
  Having a second backup of your data wouldn't hurt, especially since
 you're about to erase the original. If you don't already have another 
up-to-date backup, create one with whatever backup program you regularly
 use.
  
The Windows Reinstall
Exactly how you replace an old Windows installation with a new one 
depends on your recovery tool. If your PC came with a recovery partition
 on the hard drive, find the instructions for booting into the repair 
environment. Watch the screen as you turn on the computer; it might show
 a message such as 'Press F10 for Repair'. If it doesn't, check the 
manual or call technical support.
  If your recovery tool is a disc, boot the PC from it.
  
Either way, follow the prompts.
  If your recovery tool is an actual Microsoft Windows disc, the tool
 will ask what kind of installation to perform. You want the kind that 
gives you a fresh version of Windows. For Windows 7 or Vista, when the 
wizard asks about the type of installation, select the 
Custom (advanced) option. For XP, at the 'Welcome to Setup' screen, press 
Enter to Continue, not R for Repair.
  
Setting Up Windows
Congratulations: You have a fresh Windows installation. Now the hard work starts.
  Remember that Windows will need updating. The patching will happen 
automatically, but if you want to get it out of the way, launch Windows 
Update and take care of it.
  You'll have to reinstall at least some of your 
drivers.
 You can go back to the discs that came with your PC, printer, scanner, 
and so on, or you can download newer versions off the Internet. 
Alternatively, you can install the drivers off the clone you made before
 reinstalling.
If you reinstalled Windows from a vendor-supplied tool--one that 
returns your hard drive to its factory condition--you probably have a 
lot of junk on your computer. You'll have to uninstall the stuff you 
don't want.
The uninstallers that come with Windows applications are 
notoriously sloppy, leaving all sorts of remnants behind. I recommend 
either 
Revo Uninstaller or 
Total Uninstall. These programs run the application's own uninstaller, and then clean up the remaining mess.
The difference? Revo is free, but Total does a better job with 
uninstalls that require a reboot. Also, Revo doesn't work with 64-bit 
programs, while Total does.
Now that you've cleaned Windows of unwanted applications, you have 
to reinstall the programs you do want. Start with your security tools, 
and go from there. Don't try to install two programs at the same time, 
and if an installation requires a reboot, don't put that reboot off. 
Just do it.
  Once everything is installed, take some time to make Windows your 
own. Pick your wallpaper, change your power and screensaver settings, 
and so on.
One More Backup
You just spent a lot of time taking a fresh Windows installation 
and customizing it. If you ever have to reinstall Windows again, 
wouldn't you like to skip that step?
  Use image-backup software and an external hard drive to create an 
image of your hard drive in its current everything-but-data state. 
Should you have to reinstall again, you can use this backup as your 
recovery tool and simplify the process.
  Again, I recommend 
EASEUS Todo Backup, although you can find other good programs that will do this job.
  Whatever program you use, make sure to create an emergency boot disc with it.
  
Restore Your Data
Now it's time to bring back your data. If you used an actual 
Windows 7 retail or upgrade DVD, the data is in a folder called 
C:\Windows.old. If you used a manufacturer's recovery tool, your files 
might be in a special folder off the root, perhaps called C:\Backup. Otherwise, your data is no longer on your hard drive.
  Aren't you glad you made that backup?
  If such a folder exists on your hard drive, open it in Windows 
Explorer and navigate to its User folder (Windows 7 or Vista) or 
'Documents and Settings' folder (XP).
  If the folder doesn't exist, you'll have to get it off of the clone
 or image backup. Create a folder on the internal drive called 
Backup
 (it should be C:\Backup). Plug in the external drive with the clone, 
and copy the contents of that drive's User folder (Windows 7 or Vista) 
or 'Documents and Settings' folder (XP) to C:\Backup. Once the copying 
is done, remove the external drive (properly, of course, through the 
system tray's removal tool). Leave Windows Explorer open to the 
C:\Backup folder.
  Whether you needed to copy the data from the external drive or not,
 you should now have a Windows Explorer window open and displaying 
multiple folders--one for each user logon. For convenience's sake, I'm 
going to call this window the 
Backup Location.
  Open a second Windows Explorer window, and navigate to C:\Users 
(Windows 7 or Vista) or C:\Documents and Settings (XP). I'll call this 
window the 
Proper Location, because it's where your data 
should be--and eventually will be.
  Do the following for each user:
Open the user's folders in both the Backup and Proper Locations. You 
will see additional folders, mostly the same ones, inside each. Drag 
some of the folders from Backup to Proper.
Which folders should you move? The obvious ones are Documents, 
Music, Pictures, and Videos. Their names may or may not be prefaced with
 
My. XP users needn't worry about the lack of Music, Pictures, and Videos folders--they're inside Documents.
  You should absolutely 
not move AppData (Windows 7 and 
Vista) or 'Application Data and Local Settings' (XP). These folders are 
hidden, so it's likely you won't see them, anyway.
  Use your own judgment about other folders. Just remember that the 
folders you don't move aren't going away immediately, so you can always 
correct that mistake.
You'll get several error messages as you move the folders. If Windows
 asks, yes, you do want to merge folders. Replacing a file with one that
 has the same name is also probably safe, but use your own judgment.
That process will take care of your documents, spreadsheets, 
pictures, music, and so on. Application data (Firefox settings, Outlook 
data files, and the like) is more complicated. Each application has its 
own way of handling the task, so I can give you no general instructions.