My favorite thing about situations like this is people automatically take it to about 15 levels beyond where it needs to go.
Jason Campbell for Whitner. It's not like we're trading a first round pick for the guy or signing him to a long term deal, we're just trading an expendable part of our roster for a guy who fills a need. This doesn't mean Jason Campbell is the QB here for the next 10 years, it just means he is probably better than what we have on our roster right now, and might buy the Bills at least one more year before they have to go draft a QB.
If it works out, great...we have our franchise QB. If it doesn't? What did we lose? We traded an overpaid, underperformaning player for a guy who is immediately the best QB on our roster.
Make the move.