I'm also running iTunes 7.0.1 in RC2, and I can't hear any of the tracks in my library. The RC2 feedback tool has identified a problem, has check with the Microsoft database, and has informed me that the problem has been fixed in the full release version of Vista.
I can fnd out more from a Microsoft beta newsgroup, but I wanted to know if anyone else had the same problem first. I suspect that in my case it's an Audigy2 sound card issue.
I'm not getting anything - no sound whatsoever, although I can see iTunes happily telling me that the track is playing.
If I go to the online store I can hear samples of around six or seven tracks before the sound suddenly dies on me. Close and restart iTunes and I can again hear a few samples. I can't hear tracks from my library at all.
If I fire up my G5 Powermac there's no problem at all.
I assure you I have very good reasons for wanting to run iTunes - as do millions of other people. I use Windows Media Player 11 as well - in fact I was on the Microsoft beta panel for it - and I agree it's very good.