If space (small case) is the reason to get a single gpu mb, then go with p35.
its cheap and fast.
if you can spare an extra 30$ why don't you get sli/xfire ?
in a few months you might want to go for a second gpu.
you can find at newegg:
ASUS P5N32-E SLI LGA 775 NVIDIA nForce 680i - 139$
ASUS P5K LGA 775 Intel P35 - 126$ for crossfire.
sorry for my English, i'm from greece.