Well I most have gotten lucky before, because after I repaired my partition (more on that in the next post) iTunes basically refused to play the songs I had purchased.  If you are having a problem, this: 

iTunes Repair Tool for Vista 1.0

Seemed to fix my issues.  It was not obvious on the Apple site and some of their other suggestions didn’t seem to work (or were difficult to follow – like Deauthorize all your machines, which it turns out is impossible unless you have authorized 5 machines, which is rather difficult to do without 5 machines.).

Anyway, I hope this helps anyone out there having iTunes issues under Windows Vista.