If you have Enterprise Edition, you could use the sforce Connector to do this type of transfer.

Say Ralph1 and Bob2 were the original sales team, with Ralph1 the primary one. Now they've been replaced with Mary1 and Sue2. The reassignment of accounts from Ralph1 to Mary1 could also transfer all the contacts owned by Ralph, in his accounts, to Mary. You're left with some other contacts owned by the old Bob2.

You could produce a report of contacts owned by Bob2 (possibly limited to accounts owned by Mary1). Then change the owner of these contacts to either Mary or Sue, as desired. The change is done by overlaying the Bob2 ownerid with Mary1, highlighting these cells, and requesting "Update selected cells". -Scot

http://forums.crmsuccess.com/sforce/board/message?board.id=discuss&message.id=620#M620