centurion is a great case - i've put computers into three of them, and they're totally worth the money.
if he's running an 8800gts, 4 gigs of ram, the biggest c2d available, and your standard optical and hard disk drive, you're going to need AT LEAST 509w to cover all that - on a 100% efficiency power supply, which doesn't work. count on an average of 80% efficiency, you're talking at least 600w, with no room for upgrade. a 750 is an excellent choice. add your watts! also, yours only has one 12v rail in it - for a decent processor, a nice video card, and all that peripherals. phaw! get a bigger one - the 750 will handle everything you ever throw at it, even factoring in the efficiency rating.
the cpu fan you picked is enormous - great for a high-end motherboard, but that gigabyte that he's got will have trouble shouldering the load, particularly in a smaller case like the centurion is. i'd go for a standard circular fan with an impeller-style heatsink, rather than the enormous radiator you picked, CH.