Just what files should a Windows 9x user back up? The conventional answer ù all of them ù doesn't help if you're using Zip, SuperDisk, HiFD, SparQ, or CD-RW storage media; they're all too small to back up today's multi-gigabyte hard disks. But they can hold your most important files.

Key file protection is no substitute for full tape backup, of course. If your entire drive is trashed, you'll still have to jump through hoops to reinstall your operating system and applications. The point is, armed with a carefully planned backup of your key files, you'll be able to restore your PC to its familiar basic contours and minimise downtime. And if you accidentally destroy a data or configuration file, you can easily reinstate it from the removable media.

Round up your files

The hardest part is finding your data files, since apps tend to strew them all over the drive. For example, most Office 97 apps put data in C:\My Documents, but Outlook prefers the Windows folder for your e-mail, contact info, and appointments. To make your job a little easier, I've provided a list of files and folders to back up for default installations of several popular programs. Of course, if you've changed where they store their files, alter the list accordingly.

How do you figure out what files to back up and where to find them? With data, it's usually easy. Just head for the folder specified in the Save As dialogue box. But since configuration files are spread all over, they are more elusive, even though Windows 9x has a central repository for them in the Registry. But not all apps ù not even Microsoft's own ù store their settings exclusively in the Registry. If you don't know where to look, try this: open a program, change a lot of the settings, and exit. Then select Start-Find-Files or Folders. Click the Date tab, click during the previous 1 day(s), and click Find Now. Maximise the window so you can see the Modified column; when the search is done, click that column heading to bring the most recently modified files to the top of the list (after the folders). Among these files, you'll find one or more that contain configuration information for the application in question.

Now that you know what to back up, how should you go about it? If you've got a decent backup program (did one come with your removable-storage drive?), use it. As an example, here's how to use Iomega's One-Step Backup: from the opening screen, click Customize and the File Selection tab. Check off the files and folders you want to save. Unfortunately, One-Step won't let you select files by type ù for instance, you can't specify *.ini. Instead, you have to sort the file display by type, then go to the Windows folder and manually click each Configuration file.

Or you can copy the files directly, preferably with software that compresses them into .zip archives. This way, you can use any zip utility to restore the files. You will find WinZip 7 on this month's cover CD in the Essentials section.

Back up the Registry

You need to back up four Registry files: user.dat, user.da0, system.dat, and system.da0. If you use a backup program, it'll copy them for you. If not, remember that these hidden files don't copy under all conditions. My programs first unhide them, then copy and re-hide them.

Restoring them is also a pain ù and restoring them while in Windows is either dangerous or impossible. My programs restore them to C:\Regback; you then boot up MS-DOS to copy them to C:\Windows.

If, Heaven forbid, you lose everything on your hard drive, you may not want to restore the pre-crash Registry. After all, reinstalling Windows and your apps creates a new, working Registry. True, your new Registry won't contain the customised configuration information stored in the old one. For instance, it won't know how to dial your ISP. But over time, the Registry collects a lot of garbage, too, much of which can cause system errors. I recommend that you occasionally wipe out your Windows installation and start from scratch. And what better time to do it than when you've just lost everything?