I've been meaning to bring that up. Since when does the professional machine sport the same CPU as the consumer line? i can't say i'm complaining though (being a student and all). How bad is the macbook's graphics though?, or how good i should say.
Since it was the iBook/PowerBook G3, then the iBook/PowerBook G4 then the MacBook/MacBook Pro Core Duo and now the MacBook/MacBook Pro Core 2 Duo.
So you see it's fairly common, the consumer line lags for a little while but it eventually catches up in terms of technology although never quite gets there for raw clock speed - the Pro line is always a bit faster. It's the other aspects that make the Pro a professional grade machine.
For audio work you'd probably be able to get by with a MacBook unless you need FW800 for stuff.
The only places you're going to notice the lack of graphical ability in the MacBook are:
1. Current gaming.
2. Aperture - professional photo management.
3. Motion - motion graphics.
4. Plugging in a big external display.
Everything else should run just fine - you don't need awesome graphics for audio work.