QB's: Favre would play if he was dead, so you have Bledsoe as a backup/Bye week filler. Raiders, to my knowledge, haven't named a starter yet. That bodes well for Collins. Keep in mind his targets are either aging or unproven and he's an unmobile QB behind a talented, but inexperienced line. However, he is worth hanging onto as he may surprise.
RB's: Good news/bad news. Gibbs will run Portis till his legs come off. Pick up Ladell Betts as insurance for him. Good pickup on Chris Brown. I think he'll eventually supplant Martin as your 2nd back. He's looked good in preseason and I'm not sure what Curtis has in the tank. Thomas Jones and Foster may surprise, however I think Davis is still the horse in Carolina and the Bears ar elearning a new offense. However it is the same offense as the Chiefs and we all know how Priest has done.
WR's: Little shaky here. Harrison is top 3, but you're counting on Porter and Price. the potential is there, but they still have a lot to prove.
TE's: I'd wait till Gonzales and Williams get rolling and package one of them with Price or Porter to upgrade your 2nd WR. No use keeping two TE's. If Williams continues his play from last year, people will be interested. Gonzo's bye week is the 5th week. You may want to hold onto Boo until after that.