I have a 04 audi a4 1.8t quattro.

I really want to change the stereo on it, maybe a dvd receiver. Right now its a 6 cd changer, but if I change it to a dvd player I wouldn't have that cd changer anymore right? Is it easy to get the stereos changed at a Best Buy?

I don't know, I'm really new to this guys. Any answers and also maybe some advice on what system to put in would be greatly appreciated =]