first off an antec 550watt for 100 bucks will power theat system easily and it will power another gtx if you were going sli
get that gskaill ram ddr2 800 that was recommended
theres no reason for you to get that motherboard for what your using it for, get either a gigabyte ds3 or an asus p5b
also i have yet to hear of anyone in the world messing up a core 2 by overclocking so dont be a wuss about it