I think I have it cracked.
Situation immediately post-upgrade was BSOD every 10-15 minutes. I disabled ACPI in the OS - in the Device Manager -> Computer -> Properties -> Driver tab I updated the driver, and manually chose the "Standard PC" driver rather than the existing "ACPI compliant" one. Rebooted, it discovered the connected devices, and all was mostly well.
Removing all but essential cards then replacing one at a time cured it until the SoundBlaster 16 PCI was re-installed, then it all kicked off again. Moving that one card to the only other available slot stabilised things again. So far so good. If the machine remains stable I'll re-enable ACPI to see if it works - nice to have the machine turn itself off after a shutdown.
[Edit]
Me and my big mouth. Still, I suppose 1.5 hours of uptime is better than 0.15 !
Last edited by The Nr Fairy; 30th January 2003 at 06:43.