Nothing succeeds like mindless drudgery

It was the hard disk. Proved conclusively as when I swapped in a 'proper' Apple one everything worked to plan. All set up nicely now, with a dual-boot Mac and Linux system. I've done a couple of rounds of updating and setting up on each, but there's more to be done; specifically, while the BT Voyager 1040 PCI 802.11g card worked flawlessly on the Mac, I have to wade through these instructions to figure out how to use it on Linux. Print server works and music server works under Mac OS X. I'm off to bed now, leaving this backing up overnight.

The really annoying thing is that I thought the problem was to do with the order and/or formatting of the previous hard disk, so the previous week or so has been spent on and off reformatting it in various ways, only to discover that the Mac was picky about what drives it liked. Ah well, done now.