We've decided to go with a different template for our team project and want to move all of source under that team project. We are not concerned with migrating work items, but we would like to keep the version history of the source files, if possible. I tried the TFS to TFS migration tool on code plex and it seems to only move the most recent version of each source file over.
We are on TFS 2008 and the team projects are on the same server.
EDIT: It looks like the move function may work. I've seen some concerns posted about whether or not this moves all the history for a given file.