I have a budget of around £400 at the very max, as close to £300 as possible would be good.
As cost appears to be the driving factor Im suggesting the following, should also allow you to play other newer games OK as well. Its all from Scan because thats just who i use, again, only picked one place because if cost is an issue you dont want to be shelling out tens of pounds on P&P on top of the cost of parts ::
Asus M2A-VM AMD 690G :: Again, i serious recommend this board if you want something well featured and are on a budget. Was £20 more 6 months agao when i got mine!
250Gb SeagateYou dont save enough by lowering the drive capacity these days.
4400+ Energy EfficientThis is where there is way more scope to play around with stuff.
2x1Gb generic RAMits cheap, and it works as well as "cheap" corsair etc. Doesnt have the same warranties, and wont take overclocking though. Pay more if you feel youll need to overclock.
512Mb Sapphire 1950ProCheap and has plenty of poke for what you need. You might want to consider something else, but if you only need Dx9 compatability then this will do fine.
Cheapy Scan Keyboad, Mouse, Case and PSU kitAgain, im thinking cheap here.
Black Samsung Dual Layer DVD WriterAvoid the real cheapy no-brand DVD Writers, they get really fussy with what media they use, and the Optiarc ones are crap. Ive seen them die in under 6 months with moderate usage.
Total cost :: £301.80 including VAT and P&P.