Beast is fixed! I swapped out the graphics card, rewired some power connectors which I suspect were contributing to the interrupt problems and booted off a Debian CD and fixed the filesystem. Then I upgraded a load of software on it. Now I'm just trying to get the damn fdmf requisites to install properly and I'll have an automated duplicate MP3 finder (works by examining the uncompressed versions of any music files you have lying around and listing similar-sounding files..)
squeeza popped round unexpectedly in the middle of all this but unfortunately I was fairly tired and stuff. Need a good night's sleep :/ I'll go to bed soon.