Let me start by saying this; the Colts have more holes than people think. The Colts lack a shutdown corner, need another linebacker, need to upgrade at DT, could use a G, or T, and depending on what happens with Bethea in the offseason may need a safety because we all know Bob Sanders can't stay healthy. Raheem Brock and Robert Mathis both have contracts that expire in 2011 so DE could be an option as well.
Cornerback: Marlin Jackson is will be returning, but if you look through the group of corners there is no one I would be willing to put one on one with a top flight receiver. Lacy, Powers, Hayden, Rushing, Jackson. All except Rushing are strong No. 2 corners but none of them strike me as a top notch No. 1.
Joe Haden will most certainly be off the board by the time the Colts pick. Kyle Wilson might be an option, maybe Patrick Robinson, Javier Arenas, but the Colts have bigger needs I wouldn't bet on any of the guys being a shutdown corner. Probably they would be No. 2 corners, which the Colts have enough of.
Linebacker: The Colts could use a rotation player behind Brackett, and could use an upgrade over Wheeler. If Navorro Bowman is available he could be a good fit at Outside Linebacker. If Spikes is available he could possible be moved to the outside, and if he is available he will most likely be the most talented player on the board.
Sean Lee could be a good fit as well. Lee played outside and inside in college, though he is undersized as an inside linebacker in the NFL. He could move to the inside if an injury to Brackett required it. It's likely that solid linebacker will be available in round two and three this year so the Colts could wait on a linebacker if someone else catches their eye.
Defensive Tackle: The Colts need to upgrade their interior run defense and this starts at DT. Obviously Suh, and McCoy are the best out their but I highly doubt either will drop out of the top 10. Odrick could provide a hard working interior lineman.
If Terrence Cody is still available he could improve the run game with his 360+ pound frame. If his conditioning improves he could be a force on the inside of the same mold as the Williams's in Minnesota. Arthur Jones and Brian Price could be nice acquisitions as well.
Guard: Kyle DeVan just simply is not a great interior lineman. Iupati or Pouncey would both be upgrades, and one if not both will probably be available, but this is not a premier need for the Colts so they will probably wait until the later rounds to add a player here especially considering guys like Brandon Carter, and Jon Asamoah could be there in the second and third rounds.
Interior offensive lineman are rarely drafted in the first round and I wouldn't expect the Colts to do it, though it is not out of the question.
Tackle: Again, not something they desperately need but they could afford to sure up the LT spot. Neither Johnson or Ugoh are fantastic LT's. If Ciron Black, Bryan Bulaga, or Anthony Davis is available they would be a great option. If none of the guys manage to slip down there are still solid options but the Colts can afford to wait. It'll be hard for the organization to pass one of the guys up if they happen to slip into the late first round.
Safety: This all depends on whether or not the resign Bethea. It is either not a need at all, or one of the Colts top two or three holes. Aside from Eric Berry and Taylor Mays there are no great prospects. The Colts can probably wait until the second round and draft a guy like Major Wright, Deunta Williams, Darell Stuckey, or Rashad Jones.
Defensive End: The best fit for the Colts from the DE's in this class could be Jerry Hughes, and there is a decent chance he'll be available. Everson Griffin, Brandon Graham, and George Selvie are all solid ends who the Colts could use effectively and all could be available.
What happens with position all comes down to what the Colts want to do wit Brock and Mathis. If the organization plans to let both go (which is unlikely) then DE becomes a potential first round pick. If the organization plans to keep both it is not a need at all, and if it plans to release one (likely Brock) then the Colts could wait a year or at least wait until later rounds.
The most pressing needs are corner, linebacker, defensive tackle, and possibly safety. I don't think a top flight corner will be available, and Safety is only an issue is Bethea doesn't return, considering Bob Sanders' health problems. In the first round look for Indianapolis to go LB, or DT taking Cody, Jones, Price, or Odrick at DT or Brandon Spikes or Navorro Bowman at LB is either or available.