I bought my Zune today and rushed home to install it, only to find out it didn't work with Vista RC2. I know its beta software but that little fact could have been brought up before I paid $250. Anyways, too the good stuff. I wasn't gonna give up, so I kept playing around with the install disc and everything. This is how I got my Zune to work on Vista RC2 for me.
1. Don't let the Zune CD autorun - instead right click on it in my computer and choose open
2. On the Zune setup .exe right click and go to properties
3. Click on the compatibility tab, then check "run this program in compatibility mode for:" and select Windows XP SP2
4. Hit apply, then ok and now go back to the opened Zune folder and run the Zunesetup.exe
Everything worked for me, went right through the complete install. Let me know if you have any problems.