Will USB be sufficient for recording vocals w/ a large diaphragm mic and using midi and a guitar occasionally? This is not a big band process as most of this will be looped and sampled. I have a 1.8 G5 w/ Logic and Reason. I've spent so much dough on everything else, I don't know if I want to spend another 4-500 on a Firewire preamp.

Also, are the 5.1 speaker packages good for monitoring? Apple and Musiciansfriend both sell a Logic set for $300 and I'm wondering if anyone's tried them out.

Much Thanks!