Hopefully I will not get lynched for saying this, but you might look into Aopens line of video cards, that is if you are looking for decent performance at a "decent" cost. I am running their PA3010Pro card which is based on nVidia's
TNT2 Graphics processor with 32 megs of onboard memory. I have not had any problems with this card, and it plays Halflife pretty well. I am currently running a Celeron 500, Aopen AX64 Pro motherboard, 128 megs pc100 sdram and a 5400 rpm hard drive. (All right people, no snikering! this is the first system I have built).