I'm a fan of dual systems, but unless you like tinkering a long time with software and especially driver installs, I'd not choose SMP for an audio only machine. Can be a huge pain in the neck to get to work with 'prosumer' and 'pro' boards alike.
What I'd get is:
* Intel chipset board
* a P4 (any speed northwood will do)
* as much RAM as you can afford (buys you more "undos" if nothing else)
IMO it's more important to get the audio equipment right, cheap mics + on board sound is not a good idea only to be able to pay for a 2.2 P4. I'm sure the resident DAW gurus will chime* in if you need assitance with that.
* Can I nominate this for "worst pun of the week"?