Came in a lil late, read the entire thread, would have plumped for the HID interface...
PS/2 gear has foulups, USB does not...
ahhhhhhh, strange joys, I seem to get greif from the USB side of things, but still keep a trusty old plain-jane ps2 keyboard for BIOS boot-level troubleshooting, some mainboards are a lil slow to turn on the USB keyboard support
the PS2 keyboard also has lovely old-fashioned tall keys, great for them Phat-Phinger days...