I had much more success by adding the 64Studio repos and using the 2.6.29 kernel - and most other stuff, actually - from hardy-backports. I've tried the ubuntu -rt kernels from both Intrepid and Jaunty 32 and 64bit and they were horrible - system lock-ups, apps crashing, sync problems, MIDI problems, zombied apps, irq problems, no smp, etc, etc, etc.
Yoy will need to compile your own NVIDIA drivers (takes 5 minutes to compile and install). You should be able to run with smp and acpi again. :)
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