Also consider testing your sound cards prior to the software: if you can't get them to work, or you can't exploit very low period sizes (64-128) then all the software will come to no use. And don't forget about some tests with MIDI to audio conversion in Rakarrak at low pitches... These are the two most importante showstoppers IMO. If you want to go low latency, consider a clean distro, for some tests, I use Audiophile Linux (AP Linux), because the kernel comes patched and you have the bare minimum (also you can start with a handy fluxbox desktop manager with all the process info), or just go for a stable debian and maybe patch it RT PREEMPT. L.