I originally was using winamp as the audio engine but found it to be cumbersome, especially with updates to winamp. I found it easier/stabler(is that a word..) to just have everything enclosed within the program instead of making API calls over to another application. Also, you can use wmp for all your media needs: audio, video, dvd.

Skinning I havnt implemented fully, I've kinda put it off to the side in an attempt to make a program that looks good in all cars. It does do Night skins .