I replaced the hard drive in my machine (the other one decided to stop without reason), connected it up, switched the machine back on and it seems to start up (in that BIOS recognises the hard drive and that it is the "Master" etc).

The first error that appears is:
"NTLDR is missing. Press Ctrl+Alt+Del to restart."

After a bit of searching I found that a fix might be to insert a bootdisk. This has never had an OS on it, but previously I was dual booting linux and XP, so I put the XP disk in the floppy drive, restarted and it starts to boot from the floppy before coming up with this error:

"File \biosinfo.inf could not be loaded. The error code is 4109. Setup cannot continue. Press any key to exit."

After bit more searching, a couple of people had had success by putting their XP CDs and booting from there. When I tried this, I get the following message during startup:

"Boot record from CD..Not found"
(And the same thing happened when I put the Fedora release 3 CD in.)

I also found a little tool from somewhere which diagnosed that my "hal.dll file is missing or corrupted."