DON'T INSTALL 7.6! If you have an iPhone and you were upgrading to 1.1.3 firmware, the firmware works fine. But you are also prompted to upgrade to 7.6 iTunes and take advantage of movie rentals. Well, if you are a windows xp user and you sync your iPhone up to your outlook contacts and calendar, you're in for a few problems.
7.6 blows up sync'ing. Although contacts still sync'd, calendar events did not work at all (less than 50% of events sync'd).
To resolve things, I had to wipe out 7.6 (uninstall, delete all apple software directories, uninstall apple connector and apple updater, pretty much everything with apple in its name), wipe out the ITL and XML files from the itunes folder (in mymusic), reboot, then reinstall 7.5. Vua-la! Everything works fine.
Apple phone support tried to convince me my pc had changed. Nope. I upgraded again to 7.6 and the problems with calendar sync recurred immediately.
So until Apple releases a 7.6.1 or 7.7 or something they claim has fixed these bugs, pls don't waste your time trying to troubleshoot 7.6. There are a sleu of problems being identified for pc and mac users alike.