Best Gaming computer build for $650

OK, here we go...(im not being sarcastic)

ATI/AMD is really your only answer, for the graphics card I would go for the new 5000 series, for they are amongst the best DirectX 11 cards for the money...
I have a XFX 5770, and it runs Crysis on 1080p easily! For the CPU, its really just personal preference that you should go for, but may I recommend one in the Phoenom range(I would not go for anything other than that for they will be underpowered!)
for the RAM, any should do, but obviously DDR3 is the way to go, and its cheaper!(PS: if you go for some RAM with heatspredders, make sure they dont get in the way of the GPU, as the 5770 is rather long!)
The Hard Drive is up to you, for I dont know how much space you need. With your budget, i wouldnt reccomend a SSD, for they cost an arm and a leg at the moment!
Any case would do, but i would go for a Thermaltake M9 series case, for they are value for money...
Im not too familiar with blu-ray drives, but the best you could go for is a BD/DVD combo, so you can use DVD or Bul-ray!
In your list you mentioned nothind of the CPU cooling or PSU, but Gigabyte should do well in both those categories!!!
Also, you should add Windows 7 to your rig!!!

Good luc!

I already have a copy of win 7. I just built one on newegg for $600 flat. I have a XFX 5770 a Athlon x3 processor (i looked around on the site everybody said you dont need any more then that but i'm open to suggestions), G.Skill ripjaw RAM, a 585W hec powersupply, and the Antec three hundred illusion. The mobo i got is in a combo its a MSI 870A- G54.