Fantasy help?

Ok i have a problem. I got horrible running backs this year, except brian westbrook. I got clintin portis and dominic davis. My quarterbacks are carson palmer and marc bulger. There are no longer any good running backs available, but there are a few decent quarterbacks like steve mcnair. I am thinking about trying to trade bulger for maybe ronnie brown or willis mcgahee. Would this be a decent trade if i can get one of those running backs?