NEW gaming system build please critique

I built this build on a budget so i couldnt get 8800 but i think 8600 should suffice for couple years at least...also if my budget allows ill get the Quad core6600..id be glad to hear any comments u have on this build.. should i get this motherboard or asus ??? and is the overclocked 8600 worth the $40 extra or should i just get a nvidia 8600gt..whats the difference anyway ??

Core 2 duo 76750
Gigabyte PS3-DS3
2GB Kingston 667 ram x2
Seagate 250GB
8600GT (overclocked) XFX
Coolermaster 650W PSU
Casing - 534 coolermaster