you would need a new steerer tube and fork designed for a threadless system, new bearing, cups and shells, along with a new stem to fit on the forks. make sure your headtube has the same cup dimensions for the new system, or basiclly just get what fits right. it seems like a lot of money to spend to convert it. just don't like threaded headsets? you could get a killer new threaded headset for half of what you'd spend to get everything to change your bike over. thats just my opinion.