Older, but no wiser

This is a long shot, I know. I have a very sick PC in need of urgent attention. I bought it off eBay for my sister, complete with Win2K and license, from a dealer in ex-corporate PCs. It worked fine, I installed various bits of software and it still worked fine. Then I put in a CD writer, loaded Nero Express 6 which came with it, went to copy a CD to test it out, all still seemed fine, but after successfully copying the CD it blue-screened in a big and as it turned out very nasty way.

To cut a long (and it was very, very, tediously long, I assure you) story short, what I now have is a PC that doesn’t know it has a hard drive in. So I can’t even boot from floppy.

The last thing it told me on that evil blue screen was something like “starting physical memory dump…”

Anyone out there know how to make it recover from its amnesia and remember that it has in fact still got its hard drive there?