Hey there , If you wanna Play games with that Pc then Go for Quad Cores , 6 Cores are Not as Fast as Quads , you will ask your Self they have 2 More cores that will help , NO , It wont It s Just Good For Multitasking but For Gaming ! Only Quad Core !
For Example I got Phenom 955 BE + MSI 790FX-GD70 its cheap build & it Gives me What I want , but I should Say that you need Aftermarket Cooler because its geting Loud & hot While Gaming !
Any Quad CPU does ! especialy AMD CPus !
MSI 790FX-GD70 is Great motherboard , it has Quad Way Crossfire at 8x8x8x8x or Dual Crossfire at maximum speed of 16x16x ! it Doesnt Have USB3 Or Sata 3 , but No matter because there is No USB 3 Or Sata3 Device ! you will be Great with this motherboard . you can add other Vga card in future .
Phenom 955 BE is better than what you choosed up there , it will beat it In Games ! you can go for phenom 965 BE or 970 BE , they just have Higher Clocks But no Huge Difference in game .
But away if you have more money then Put it For Cheap Sandybridge Platform , for example i5 2300 or i5 2400 is Much Faster & Great For Today games . But that doesnt Mean Phenom 955 BE is bad , its great too but i5 sandybridge is Just better ! Both will give you what you Need .
I suggest you pick 2x2Gb DDR3 1333Mhz ram . supertalent , Geil , Corsair & ... are great . dont Pay too much for Ram .
Your PSU is Great for Crossfire too ! its Nice one .
& for VGa card , go for ATi 6870 or Better , because ATi 6870 is Very Great but it Runs Crysis Warhead at 30-40 FPs ! & you Know Slower Card realy doesnt worth ! you can Grab 6950 for almost same price , 2Gb is Available too but NOt Too much difference , if you have money then 6970 will Rock ! i have 6870 & it runs all of my Games at 70 Fps except Crysis Warhead which is 30-40 Fps & GTA EFLC which is More than 40 ( its Playable & Great enough ) ! dont Worry ! 6870 is More than Enough for Today games ! but dotn foget 6950 & 6970 are available if you want more performance !