Outlook-to-GPE-and-back is doable, actually. Acrobatic but functional, and mostly automatic.

You need a Google mail & calendar account. First you sync your Outlook calendar with your Google one using the Funambol plugin, through a proxy account at ScheduleWorld, as explained here :

http://tinyurl.com/zl7e7

After that, you can sync your GPE calendar with the Google one using David's Erminig.