Well if my memory serves me correctly a Raedon card, ATI based isn't it?
For you early steps with mandrake, I'd actually suggested getting hold of a "boxed set". That's what I did to start with as I didn't know enough to get the nvidia driver up and running, but the boxed set has them already configured - I'm not sure but I think that it's the same for ATI based cards as well.
You don't get them with the download version as they're proprietary (even though the nvidia driver is available for download from their site, along with instructions).
You might want to check out mandrakes site to see what they say. If i'm correct, it's worth the money just so you get to start your linux life relatively hassle free. Then when they issue an updated kernel, if the ATI driver is managed in a similar way to the nvidia one, you have to re-install for the new kernel - worst case then is to just re-install from the original mandy disc if you mess up.
Heres a link
about how you might go about getting this sorted if you didn't want to try the route that i suggested above - It looks like it'll still require some reading though.
Sorry I can't be of more help (never had an ATI card, and probably won't as nvidia support of linux isn't perfect, but it's better than ATI).