itunes doesn't recognize iphone 3gs

Please help!

Since the latest itunes upgrade, my iphone 3gs is not recognized by itunes. I am unable to sync or do anything! I have tried the following:

Uninstall itunes and reinstall

Uninstall Windows Media player

Uninstall Quicktime and reinstall with itunes 10

Stop and Restart in Administrative Tools

Disable all but itunes helper and Qttask in msconfig., restarted, still nothing.

Installed and ran updated gear drivers from gearsoftware.com.

I used to get the error message "itunes was not properly installed, if you wish to import or burn CD's you need to reinstall itunes". This was fixed with the gear driver installation but still no recognition of my iphone when I plug it in.

No matter what I do, it doesn't work! Any help is greatly appreciated.

Windows xp Service Pack 3

Thanks.