I have a similar question, but my uses are a bit more intense. A bit of intro:
I have a 2007 MBP (pre unibody) 15", 2.4ghz Core 2 duo, 8600M GT. I use it for the web, music, video, word processing, coding, virtual machines, basically the whole gamut except gaming.
I am fine with its performance.
However, the laptop is getting old and I'm nearing the time for upgrade as I don't think it will survive much longer. My question: do you guys think the 13" Macbook Pro will manage to perform as well as my old 15" model? Specifically, will the 320M cause me any problems if I'm not gaming? How does it compare to the 8600M GT?