If you want to use Google Calendar sync with Outlook on Windows 7 (64 bit) you can get the error “Could not connect to Microsoft Outlook : error -2146959355″.
There are a few steps to fix this.
1. Repair Outlook. Click on Start, Run and type in appwiz.cpl and hit enter. In here find your Outlook (or Office) and up the top click change. In the install window that appears choose repair.
2. Repair your PST. To do this use Scanpst.exe that is installed with Outlook. With Outlook 2007 this is in Program Files (x86)\Microsoft Office\Office 12\.
3. Change a registry setting. Click on Start, Run and type regedit and hit enter. Find HKEY_CLASSES_ROOT\TypeLib\{00062FFF-0000-0000-C000-000000000046} and rename the key 9.3 to 9.3.do.not.use. Close regeidt and try again.

WARNING : Do not edit anything else in the registry, changing the wrong thing can stop your computer running completly, so be careful.

After all these steps your Outlook calendar should now sync with your Google calendar.