The Cards have put themselves in the position that in the "impact" round(s) of this draft (namely rounds 1 and 2), they won't have to pick for need, and can pick the best player available. Some question of "need" will come into that estimation, but Graves and Green have done a good job of minimizing that.
With that being said, I think that the Cards need good players at these positions, in order of importance:
(1) Playmaker/catalyst/leader on Defense, regardless of position. Personally, I'd prefer a middle linebacker who can blitz, cover, and defend the run, but anywhere.
(2) 2-Gap Defensive Tackle. It all starts up front. A good 2-Gap player will make the entire defense better.
(3) Cornerback. Renaldo Hill might be gone after 2004. Duane Starks is a question mark. It's essential that the Cards get some young players to re-stock the larder.
(4) Runningback. I'm not sold on Marcel Shipp as the answer, especially in Dennis Green's offense. The Cards need a home-run threat at tailback.
(5) Middle Linebacker. It's a travesty that Ronald McKinnon is a starter in the NFL. If he's still starting two years from now, the folly will be compounded. He can only do one thing. He'll be a great special-teamer and wave player, but he shouldn't be starting
(6) Speed wideout/Kick/Punt Returner. If DG's going to run a 3WR base offense, we'll need someone that defenses will have to respect coming out of the slot (we're rolling our eyes at you when you raise your hand, Mr. Gilmore). If Az Hakim is released after the draft, he could do well. If not, Dennis Northcutt could probably be had for a 2005 third-rounder.
(7) Offensive line depth.