I have been having a heck of a time with music on my Vista Ultimate setup. I did some digging and it turns out there is a known issue with Nero where they whack some regkeys and it messes it all up to hell. In my case every so often when I go to the music library its as if I have no music at all then it has to reload in the library which it does in like 1 minute and I have >50gb of music.
I just did this and rebooted and the library seems down right snappy again.
Anyway here's the post with the details. Set a system restore point before touching the registry.
http://www.microsoft.com/communities/newsgroups/en-us/default.aspx?dg=microsoft.public.windows.vista.music_pictures_video&tid=5208cf15-6a51-4668-bb7c-ef12d3f8c137&cat=en_US_9CA88DDB-D18D-FA0E-A366-6E527B0FBA67&lang=en&cr=US&sloc=en-us&m=1&p=1
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