Im buying an ati/amd 5830 or a 6850, so igp isnt really a selling point. in my area of the world, gigabyte and asus motherboards tend to make up the majority of motherboard sales so those would be the boards i would be looking at.
Regarding cores, im buying 4 cores for the 'future', just so the pc it lasts a bit longer without being upgraded.
As far as games, crysis 2, metro 2033, dirt 2 etc.