Simple really - you don't want to lose your data files in particular if something goes wrong. Even though you may have a 'static' setup which is usually pretty stable (ie, one which does not have other programs, updates, plugins, demos and so on being loaded and uninstalled fairly often), lots of things can go wrong.

Other people - enthusiastic children especially - are prime suspects for system failures. If they don't know your setup, they may delete files they think are unwanted (aaarrghhh!), change system settings, install unstable or incompatible programs (games, usually) and bring about a crash. With luck this will not affect your data files, but if you can't use Windows to get to them to make copies before doing a total re-install, that is not much comfort. Trying to recover them all via DOS - from a bootable floppy - really is no fun at all!

Hard disks can and do fail. ScanDisk will often provide advance clues as to the state of a drive; bad sectors should be an immediate cause for concern. But they may just give up without warning. No manufacturer will accept responsibility for more than replacing a faulty drive under normal warranty terms; they will not try to recover lost data. Firms who specialise in this are expensive. Specialist software run from DOS (using a floppy to bootup), may be able to recover something, but there are no guarantees with it.

A power surge or 'spike' due to a fault in the supply can often be fatal. A lightning strike definitely is! Fit plugs which immediately cut the power link to the machine, printer etc to protect your PC against power surges; a powerful spike may nevertheless fry its innards.

You probably power down and unplug your machine if a storm is raging right above you. Do remember to unplug the modem's phone connection, too. A spike from a hit miles away may not affect a standard telephone, but can knock out modems.

More mundane accidents happen. They vary from the physical (a spilled mug of coffee) to the merely human (eg, you accidentally delete a whole folder instead of just one file, or select the wrong file to delete, and then clear the Rubbish Bin).

There are some suggestions you might care to consider in the Preparation section to "Re-installing Windows9x". Most software-related suggestions there are for the specific purpose of easy re-installing; but they should be done as one-offs if you have the space. For Routine Maintenance purposes, however, I suggest the following:

1. On the Start Menu click Run.
2. Type     regedit     in the box, and click OK.
3. On the Registry Editor Menu ask for " Registry " - " Export Registry "
4. Under     Range     select     All     and type a name in the box with something to indicate the date (eg    Nov2001.reg   ).
5. Browse to a location to save the file and click OK.

This depends upon how much use is made of the PC. Once a week for a hard-worked business machine doing letters and reports, updating spreadsheets and databases, and so on is a maximum; daily would be better, at least for the most used files.

If it is a less used home PC once a fortnight would probably suffice. In any case do not do it less than once a month.

Projects being designed should be backed up frequently, preferably after each session. It is surprising how many changes can be made to groups of files being created to work for a specific purpose such as databases and their interfaces. It may be more convenient in such cases to simply copy the latest versions, preferably to a separate drive or a floppy / ZIP disk.