How do I register my computer for syncing?

How do I register my computer for syncing with outlook 2007. I am using a pC with Outlook 2007. I set up Mobile ME on my new iPhone 3G and it syns with Mobile Me, however when I go to the set up Mobile Me on my laptop, a windows pc with outlook 2007, I go to the sync tab on the preferences, check off Sync with Mobile Me and an error message comes back saying that it is unable to register this computer for syncing, Please try again later.

Am I doing something wrong or what?