whilst on the topic of upgrades, I am wondering which of this should be replaced, I can only run Clod at ~20-30fps with huge stutters.

ATI RADEON 68701gb
Q8400
4gb ram
500W homebuilt power supply :cool:

Hmm, you should get more frames out of that system. The Q8400 is quadcore at stock 2,66GHz. You should be able to overclock well over 3 GHz.
Your g-card and ram is sufficient for max settings.

You're running XP? At what resolution?

Other thoughts
 

Dave,
I don't recall the tdp of that cpu, however likely that your pc only draws 300 - 400 watts max, max!

How mush was the ps, where did you buy it, who is the manufacturer and model number?

If one assumes that your ps is a quality/reliable manufacturer one it should not be a limiting factor. However most ps that the average joe buys at best buy and the like are junk if they are priced under $100+ FOR THAT WATTAGE - PS are not created equal, of significant importance is the actual manufacturer and the reliability, voltage control of the ps.

Never cheep on the ps, and do the research before you buy.

Others may differ, but my recommendation without further info on your ps, is that >> if << you cannot drop a quad in your existing mobo, you would need a new mobo. Never just replace mobo, i always recommend reinstall of os.

Right i've just picked up a phenom 2 quad core and have updated the bios to accept am3 cpu's. If you don't hear from me again, it's all gone horribly wrong.

Or you're in aw over the beautiful game and fps over 60 avg. :-D

Didn't go quite to plan :( My motherboard can't take the new 125w cpu and shuts down straight away. Oh well looks like i need a new motherboard and ram after all.

Got my new motherboard, quad core cpu and 8gb of ram installed and it even boots up and runs fine without having to reinstall win 7. I am now happy to report i an getting around 45 fps average which is soo much better than before. Off to play some more.
Thanks for all your help :)

Running win7 x64, unable to overclock (possibly due to bad motherboard? It was fairly cheap) past 2.67 :(.

I don't know what to do, it avgs around 25 and often goes lower!