I would avoid dual-core notebooks for now; I've used a 1.6G Intel duo on a Dell notebook and its very laggy, espiecally when you're running a few applications at once. I would suggest a single-core 2.0G AMD processor (thats what I have, and I sort of prefer AMD from the get-go). I am no expert on this, but I guess that the problem with duo-core is that its hard for them to run certain programs on one processor versus the other (it seems like they can't decide which processor to run it on at one speed so they switch from one to the other, and that takes time).

Go with PC, iNotebooks suffer from the same pitfalls as all Macs... nobody really makes good applications for them as they make for PC.

My favorite recording software is WavePad, it has lots of features on it for tweaking.