The easiest step would be to simply plug in a different keyboard and see if it works. Keyboards do fail just like any other device.

ungua,

You seem to think the keyboard isn't working because of deleting some files in windows. Your PC doesn't really need a driver for the keyboard; it will start working the moment the machine reads its BIOS. (The exception would be USB keyboards, which some BIOSes don't know how to work with.)

Try hitting delete, F1 etc before the machine finishes its POST diagnostics, and you should be able to get into the BIOS to see whether the hard drive is recognized correctly from there.

--Shade

@shade, it turned out the keyboard was physically damaged. and your advice won't work on a system with no working keyboard - as i said before. the problem with some old compaq systems is that they write some bios information on the harddisc, so formating the hdd will cause serious problems. luckily, this was not the case with this machine.
my roommate decided to install xp again instead of windows and so to use a lot of his time waiting for applications to start. i want to thank everyone anyway for giving fast and constructive response!

regards
ungua

Perhaps you dont need this anymore but I just wonder how can he tolerate running win xp on 80MB RAM...

Maybe the best way to help your friend is to do some research on boosting xp performance, like switching to the classic desktop, some RAM utility that flushes the RAM when necessary, etc. This reminds me of the old days, though :P When computers usually dont have enough RAM...

i totally agree with you! seeing this computer reminded me a lot of my own pc-history, with problems that seem forgotten now (commodore amiga500, p66 + 8mb ram, later my first modem with 28k *woohoo*). i can advice him on performance tools, but i really doubt he is going to have the system up and going for a long time anyway because he downloads about everything he comes over; which is simply dangerous using windows.

regards
ungua