Installing software is dangerous. Every time you put another program onto your system, you run the risk of breaking something that's already there. And uninstalling a new app doesn't always fix a troublesome installation, because uninstall routines seldom do their job completely. So, how do you install new software without risking disaster?

One way is to use PowerQuest's SecondChance (FIGURE 1, top) or Wild File's GoBack (FIGURE 1, bottom). These programs track all of the changes made to your hard drive. If an installation messes up things, either program can roll back your hard drive to an earlier condition.

A word of caution: before you use one of these programs to restore your setup, backup your data. You might want to get Windows back to where you had it last Tuesday, but you don't want to lose a week's work in the process.

If you would rather not spend money or risk installing these programs, you can simply back up the Windows Registry before installing a new piece of software. This won't protect you as well as GoBack or SecondChance, but it will let you restore the part of Windows that sustains the most damage after a bad installation.

You can backup the Registry in Windows Explorer. Select View-Folder Options (or View-Options). Click the View tab, select Show all files, and click OK. Now create a folder called C:\Regback. Go to the Windows folder, find the files system.dat and user.dat, then hold down <Ctrl> as you drag those two files to C:\Regback.

If you need to restore the Registry, you must first exit to DOS. Do this by selecting Start-Shut Down-Restart in MS-DOS mode. At the DOS prompt, type the following commands, pressing <Enter> at the end of each line: