(My) Successful Sync Solution
First off, I want to thank all you guys for the many great tips, most all of which I think I tried, unfortunately to no avail. My issue was the same as many of yours'. Contacts were fine, but Calendar would not sync. I did not experience the crashing of Outlook, nor disabling of add-ins, but the syncing would never actually do anything. My final solution, which I got the idea from the AT&T forum, believe it or not, was to uninstall the "Outlook Live Search Maps Add-In." Disabling it was not enough, it needed to be removed altogether. All other add-ins remain installed and checked. The calendar now syncs perfectly. Events created on either side sync to the other. I highly recommend trying this, if you have that add-in installed. As I said before, I'd previously tried almost every suggestion, even the new pst file and uninstall/re-install type solutions. In the end, for me, it was just this one add-in.
Interestingly, I have not read others complaining about another issue I've had since the beginning, which is that, if an iPhone is connected to my PC (either my laptop, or desktop), and iTunes is running, upon eject, or closing of iTunes, iTunes freezes. I have to kill it with Task Manager. Anyone else experience this? Despite this issue, the sync does work just fine now.
I'll cross-post this, so all can see; sorry if you see this post multiple times, I'm just anxious to spread my success

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Oh yeah: Win XP, Outlook 2007, newest iTunes & iPhone s/w.