I a bit confused here, since I don't you winamp so I don't know it structure. You stated that you want of your music data in one directory/folder. iTunes does that also, except for one thing. In that directory/folder is a directory/folder for each of the album you have. That seems like the best way to organize your music to me. Dumping all of your music in one directory/folder is dis-organized to me. But everyone is difference. You like to change the interface (skin), others don't. Thats okay. Since I don't use iTunes that might either, I can tell you much about the set up. I Like my big stereo system for my music.
Look at the iTunes preferences, you may be able to set it up the way you want, except the interface changes.