Just read on NFL.com that sproles is going to become a free agent http://blogs.nfl.com/2010/02/26/chargers-to-let-sproles-test-free-agency/. I know we wouldn't join the bidding war, but that's an ideal #2 Rb.
The other good news with all this is the Rb free agent market is getting bigger and bigger. Thomas Jones should join the list soon. You never know maybe you get a decent Rb for a decent price in this market this year and save another draft pick for a different position.