You don't really need a top end card for Racer. Sure, more power will give you better framerates and a lot of people run games at higher resolutions now, but for most stuff an older good card will be plenty. If you're playing commercial games then it's a different matter, some newer games will stutter and slow down even on high end hardware.
If you're on a budget, you could go to good old Fleabay and pick up a processor+gfx second hand, as long as you buy from someone with good feedback you should be fine - I tend to sell my old computer parts for a few ££ when I upgrade, seems a waste to bin them, someone gets some good parts cheap. Not sure I'd chance buying second hand RAM but for other stuff it's fine.
Just my humble opinion but a 9800 is the lowest I'd go, go higher than that if you can. More memory comes in handy if you load lots of textures, or have a lot of large textures, I remember the difference that going from 64-128mb made when I used to play Unreal Tournament..