Do NOT buy an FX unless it is the ultra (read: pricey) version. The non-ultras are the equivalent of the old MX series GF cards (in other words, they are shite).
GeForce 4 Ti4200-8x 128MB DDR AGP" for £75
I have this exact card, and I have a 1.4 GHz computer with 512MB ram. This card is a brilliant card, but only if you have an 8x AGP compatible motherboard, other wise it’s still a great card, but may not quite cut the mustard in some of the heavy processing games (much like HL2, Doom3, etc will be). If you have 8x AGP board then this card will run HL2 quite happily. The only drawback is it’s a DirectX8.1 card which means some of the REALLY advanced DX9 features aren’t supported. In HL2 terms this means two differences - the aliens won’t have that shimmer effect on them (but the scenery will) and some of the terrain features like foliage will be reduced in draw distance (no biggy).
If you want cheap then get that card, I can run most of my games in maximum resolution (that my monitor can handle) at great framerates. Only the latest crop of games can’t run in stupidly high resolutions, but I still can run them in 1024x768.
btw - I hate NVIDIA - when I bought that card it was £145 :disgust: