Motherboards that are compatible with AMD Athlon II X4 640 Processor

Ok, so I'm trying to build a gaming rig on the budget on $400.
I currently am getting the AMD Athlon II X4 640 Processor and the GTX 550 ti, but I'm not the one building it.

I was wondering what kind of motherboard would I need that would be compatible with that processor, and I'm pretty clueless to this because I'm new.

Basically I need someone to direct me to a motherboard that is compatible with the AMD ATHLON II X4 640 processor and tell me what exactly I would need to install my GTX 550 ti.

I'm really on a budget guys and can't afford anything more expensive than $400.
Btw, the PC I'm upgrading is this one http://www.pcworld.com/product/31140/compaq_presario_sr... .


AMD Athlon II x4 640 Processor: $90
GTX 550 ti: $90
Case: $80 (Gotta get it back from this guy who was fixing it)
Motherboard: ?????


Look at the specs of my PC and tell me if I had a decent processor and that GFX card could I run a game like BF3 and what settings would I run it on? And I would also like to know what else I might need (I'll get a mouse and keyboard eventually) like what resolution I would have to play on to get maximum quality and fps.


I'm new to this and excuse me if I sound like an idiot  .