The Slackware 12.1 install went absolutely smoothly, although it used all three CDs, whereas the 12.0 install just used two. The ancient Tseng ET6000 VGA card wasn't supported by the 'tseng' driver in X-windows, but the generic 'vesa' driver worked OK. I installed a FireWire card and a Brooktree TV-in card, and both were recognised. But a Pentium II at 266MHz is a seriously slow machine nowadays! Will install on the real Linux box next, once it's backed up.
Meanwhile, I've uploaded the Dorkbot Bristol photos from last week to Flickr:
http://www.flickr.com/photos/anachrocomputer/sets/72157606962024760/