If you only wanna spend 150 (pounds) I'm american, you probably won't be able to get a card that will be able to run Doom 3 at playable frame rates without it looking like absolute crap. How much is 150 pounds in dollars?
Windows XP Home
P4 1.6 GHZ
nVIDIA GeForce 2 MX 200
Viewsonic 19" a90F CRT
I have had this rig since December 2001. I'm working on a new gaming machine that will dominate ALL!