MSI P45 diamond

Intel Core2Quad Q9550

Radon 4870 512 GDDR5

Antec Twelve Hundred

Antec 850W Power Supply

320gb WD HDD 16mb / just a temp one till i get my raptor

So i need your guys/girls help with 2 things

Ram - mine takes up to DDR3 2000 - How much and then reasonable speed


thats about what i am running, but from what i hear, there are some games that dont like to run on vista 64 bit, i am thinking about putting in like 4gb of ram