windows xp platform. since updating to itunes 10.7.0.21 I have been unable to sync my iphone 3g via the usb cable. it shows up in my computer, but not in itunes

I have run itunes diagnostics and when it gets to connectivity test - ports, it says no iphone found. I followed the troubleshooting steps there, but have been unable to resolve this problem. I have also tried:

1. Stopping and restarting the apple mobile device program.

2. Deleting temporary files.

3. Checking the registery files.

4. Uninstalled and reinstalled itunes 2 times.

5. Used msconfig to disable start up items that could be interfering.

I'm tired of waiting for itunes 11, hoping that it might resolve my problem.

Is there a place where i can download the previous version of itunes 10.6 to see if this may help?

Thanks for any other ideas.