Currently I believe my ancient 2-core is bottlenecking my system, and it certainly doesn't play nicely with Warzones.
I'm looking for a CPU, preferably AMD, that will work well with Skyrim (and the Warzones mod), while matching the rest of the PC, meaning I'm not after something ridiculous like an i7.

Current specs
OS: Windows Vista Business 32-bit SP1
CPU: AMD Athlon II X2 255
RAM: 4GB DDR3
GPU: XFX Radeon HD 6850 1GB GDDR5
PSU: XFX Core Pro 650W
Motherboard: ASUS M4A78LT-M

New CPU: AMD Phenom II X4 965
Aftermarket fan: http://www.amazon.co.uk/Arctic-Cooling-Alpine-Pro-Cooler/dp/B002CIDIPW/ref=sr_1_1?s=computers&ie=UTF8&qid=1331062793&sr=1-1

That CPU seems to match quite well, but it's nearly 4 years old. I've noticed it's quite popular over on the Nexus, in PCs with similar specs to mine.

Does anyone have any better suggestions within a similar price bracket?