Hello, and welcome to LQ.
Please, when posting try to choose a helpful subject - this will help attract people who are best able to assist you with your question.
OK, to the problem at hand. When you say Linux can't find your audio card, what do you mean... Are you running Linux from a LiveCD? Have you already insalled it? In either case, which distribution are you using (and version)? What type of audio card do you use (I think the ATI Radeon is the video card, not the sound card).