im not firing on all cylinders this morning...
there are two ways to force contact overwrite on the iphone
1) the dumb way...(the way i did it)
make sure you google contacts are backed up
delete all windows address book contacts, sync the phone with windows address book, empty so you will lose all your contacts
then sync it with google, it will ask you to merge or replace, hit replace.
2) the easy way...
in itunes, scroll to advanced, lower part of the info screen when you have you phone up and click, on next sync replace the following on the iphone with ____ from this computer.