We did the same thing with our CPU. I actually built our main tower right into the cabinet, and hooked the audio coming out of the sound card into the aux on the Sunlines stock radio.
When we're sitting around for the day, we have MusicMatch on our CPU that has thousands of songs and various playlists to suit any mood. THen we can just hit play if we want to hear some good relazing fireside music, or if we're getting fired up for the evening and have some guests over, we can play some more energetic music....etc.
Great advice, and glad to know other people are using the feature. I never thought about the audio book thing. We'll have to give that a try.