Diaw is way way better than Vlad Rad, but asking for him would be asking too much.
Gerald Wallace is too good to come off the bench.
Gerald Wallace is probably questionable as a SG. He plays SF and even PF at times for the Bobcats, after all, and he's not that great of a shooter - more of a driving / transition threat.
I'd love to get Raja Bell as a backup SG.
Diaw would actually be a great acquisition for the team because he can play SF, PF, and even C if necessary (he played C for the Suns at one point and did okay).
Bell, as I said, would be a great backup (but a substandard starter).
If somehow we could make a trade where we get Bell and Diaw off the bench and still have a solid starting SG, we'd be in great shape. We'd still need a backup PG (assuming we don't keep Marbury) and a backup C with length, though.