Following this thread with interest as since updating to iTunes 9.0.0.70, the artist names and section headers in the iTunes store now look like this -
http://www.stevenforbes.com/itunes.jpg.
Deleting fonts isn't a viable solution for a problem that is exclusive to iTunes 9. Performing a system restore to a date prior to the iTunes update would also be inconvenient to say the least.
I buy a fair amount from the iTunes store but won't be until this gets sorted by Apple, perhaps an update will be released shortly containing the fix.