AMD CPU for gaming

[RumbleBee]

Hi,

Currently have the following motherboard/Cpu combo
Gigabyte GA-M68M-S2P GeForce 7025 Socket AM2+
AMD Sempron 140 2.70GHz (Socket AM3) Processor - Retail

I was using the above system as a server, but now I'm making into a 2nd gaming machine for my son and so going to replace the CPU. Having looked at what is supported I've narrowed it down to two choices.

1 - AMD Phenom II X2 Dual Core 555 3.20GHz Black Edition (Socket AM3)

2 - AMD Athlon II X4 Quad Core 640 3.00GHz (Socket AM3)

They are a similar price and so can anyone recommend which is preferred.

This will be for pretty much games only. I'll be paring it up with a mid range graphics card.

Existing Components
Coolermaster Elite 335 Case - Black
Corsair CX 400W ATX Power Supply (CMPSU-400CXUK)
Kingston 2GB (1x2GB) DDR2 PC2-6400C6 800MHz Single Channel Memory Module
Monitor will be 1600x900 Resolution

 

[RumbleBee]

Thanks for your reply.

Games he will wanting to be play
All the Valve games
New Batman game due next year
Sims 3 expansions as and when they are released

I forgot to add I probably won't be overclocking, but the unlocking sounds like an option.

 

[RumbleBee]

Yes I forgot about the RAM. I'll be upping this to 4gb too.

The graphics card I have considered is
Asus GeForce GTX 460 Direct CU TOP 768MB GDDR5

 

[RumbleBee]

Thanks for the replies all.
I'll check the motherboard version when I get home