The problems we see with Adaptec 2940(U) controller variations cannot be just
the controller, I think. I have a PC at work with a 2940 and a PC at home with
a 2940U. The 2940U works at home, not at work; the 2940 doesn't work either
place. I just upgraded the motherboard at work from P66 to P133 with the
Triton chipset; the 2940 now seems to work just fine.
My suspicion is that we have a problem with the PnP capabilities of the BIOS
on the various boards causing the stuff to not work correctly in some cases;
of course I'm no hacker, so that may be a bunch of BS.