Whoa, this topic is unhelpful for the OP.
Some help:
800 Watts is overkill. Your rig needs 550 Watts MAX. More than that is not necessary.
Your CPU is okay, but for a better price/performance you should go for the Phenom X3 Black Edition.
Three cores is enough for a gaming rig.
Then, go for either a 9800GTX or a 4890/4870, because those are the two competing cards, and the 4870 is only slightly slower than the 4890 (again, a much higher price/performance rate).
PSU should be 550 Watts.
HDD could be anything. I don't know how much you download, but 320GB is enough internally, because external is just as fine.
Read reviews for motherboards. Some suck, some don't. I can't help you with that, though.
As for RAM, the Buffalo Firestix are incredible. 2x2GB is enough for a gaming rig.
That's pretty much everything I can help you with right now. PM me for more help, if you need it.