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:
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.