Basheer,
It would help if you provided information on your specific video card so we can better help you. I can tell you that this subject has been discussed extensively in
this post.
I don't have an ATI card but it seems that it is a little more difficult to get these drivers working but not impossible. Check out the post above first and read the ATI specific section.
This along with the follow up posts in that thread should help you to get it working properly.