I would hold onto Vidro, you knew drafting him that mostly all you would get from him would be a BA near .310-.320 and some runs. He might not get you as many runs early, but dont be surprised to se him traded before the trade deadline.
Cabrera at 3B you might see about trading, he's young and might not produce all season. But he's better than many options you might have. Hold onto Furcal until Nomah comes back and maybe package him and Cabrera for a Rolen or Chavez.
I personally like Berkman a lot, and I think Burrell will be closer to 2002 then 2003. Andruw Jones will give you 30ish HRs and 100ish RBIs with a .270-.280 BA, no slouch there. Giles you might consider moving while he's hot for an upgrade. IF you can Guillen should be fine as a Util guy.
Drop Biddle. I dont think Graves or Benitez will keep up the way they are pitching for a season, with their history. Maybe you can try to upgrade them. I might try a Loaiza/Graves deal to get another SP/RP. Buehrle and Lieber should be fine, hold onto them. I like Milton a lot personally, a Wakefiled isnt bad either.