Thanks for that info. I'm not too sure what my budget is to be honest. Maybe £80 or so. At the moment I have an Nvidia GeForce MX420 which has served me just fine until now (had the PC for 2 years). I'm actually surprised at just how poorly Doom 3 runs even on the lowest quality settings. I have 512MB RAM and a P4 2.4GHz processor so I'm hoping I don't need to start upgrading that.

I'll probably stick with what I know - which is the Nvidia cards. What about an NVidia GeForce FX 5500 (256MB)?