LenDale White isn't worth the #5 (at least, he's not worth it yet -- we'll see after the combine). Packers actually have a wealth of RBs (that's what happens when you end up with SEVEN on the IR last season) ... and while they would've taken Bush if he had fallen, defense is their main need (unless Brick had fallen, of course).
I could've gone with either Williams or Hawk with this pick. I think, though, that with Nick Barnett the Packers needed to focus more on the D-Line. Kampman is likely gone and KGB, while an excellent pash rusher, needs someone on the other side of the line to help free him up. Williams is the kind of player that can stuff the outside run as well as torment the QB. The Pack are more than happy to take him here.
EDIT: However, remember that both Davenport and Green are UFAs this season. Green is definitely on the down-side of his career, and Davenport has never shown himself to be more than a situational runner. When April comes around, the Pack may be drafting LenDale White here. But I doubt it.