EOS 1D Mark 2 - Sports 8MP/8fps/1.3
EOS 1Ds Mark2 - Studio, Landscapes, Stock 16mp/4fps/full frame
EOS 7D - a little of each very well, does video too 18MP/8fps/1.6
Like others, if the goal is sports, 1DMKII for focus speed, durability, weather sealing and image quality. If you want the best picture quality, you will give up some burst and focus speed 1DS. The 7D is not the same as the 1D models, however it's kind of between a 50D 1.6 crop and a 1D 1.3 crop for speed and image quality. 7D has dual digic 4 processors, latest technology for focus and exposure control.
Personally I consider the 5D and the 1Ds to be in a different category of camera where neither was designed for fast focus, high frame rates, or outdoor maneuvering. I'm of the opinion that these are both best suited for studio work or tripod mounted scenic and urban shots. They are full frame cameras, which is very nice. Not your sports model.
In any case, whichever you decide, one model will not do everything best. That's where you need to decide what you want to do with the tool, that suits it's features. I suspect that whatever you decide you'll be happy. They are all fine pieces of equipment.