What feature of MobileMe can sync the contacts?
On your Mac, simply open system preferences and click on
MobileMe, then make sure you are signed into your account, click on
the Sync tab and select which items you would like to sync, your
contacts from Address Book are listed in this area. On your PC,
simply open Entourage, or Microsoft Outlook and open your contacts
folder, open settings and click on the MobileMe tab, check the box
to sync your contacts with MobileMe. You should ensure that you
have your MobileMe account installed and working on your PC before
you attempt to sync any data. All data that is synced with MobileMe
is held stored in your account, accessible from any machine that
has been authorized to access your account.