You still need a fork, stem, bars, grips, seat, seatpost, seatpost binder, grips, tubes, wheels and chain, just off the top of my head. I would strongly recommend stepping downfrom XTR to XT or LX, which are still pro-grade parts, but at a much lower pricepoint. XTR is great, but if you aren't a pro-level racer or someone with a pile of cash, it's a bit overkill and you won't notice much difference in performance, if any. Remember, XT was Shimano's top of the line for years.
Second, I would also match the front and rear brake. It's not a necessity, but it will simplify things for you and probably look less parts-bin. cs1's idea of a full build kit is a pretty good one, although there are less expensive options than Colorado Cyclist.