Socket 939 upgrade?

[Ole]

My current spec:

AMD Athlon 64 3700+ San Diego 90nm (Socket 939)
Asus A8N-SLi SE nForce4 SLi (Socket 939) PCI-Express Motherboard
GeIL 2GB (2x1GB) PC3200 Value Dual Channel Kit CAS3
OcUK GeForce 7800GT 256MB GDDR3 TV-Out/Dual DVI

It runs most games I play fine - FM08, WoW and Civ4. But i've started getting into COD4 and it doesn't run particularly well, and I have to have the settings pretty low. I am planning to build a new system in about 8 months time, but I just want a CPU upgrade to last me until them.

What would you recommend for me? Any help would be appreciated.

 

[Ole]

So would you all agree that an X2 3800 would be enough to improve my COD4 experience significantly until I build my new system?

 

[Ole]

one of the later (ie. newer) E6 revisions if

How do I find this out? I am looking for one on a certain famous auction site but not sure how to tell, thanks.