The sensitivity problem is a common issue with the new Microsoft mice with the dual axis. I would have mentioned it if I had of seen this thread earlier
Anyway, what the problem is that they couldn't use the normal stopper that tells the mouse when the wheel was moved, so they had to switch to a new way. This new way blows for games, but perhaps if you feel up to it you could open the mouse up and mod the wheel so there is a bit more resistance on the wheel. A piece of plastic crazyglued to the bottem of the mouse and riding on the wheel might do the trick, just a thought.