The big trick is figureing out what gears you need. That's a question that only you can answer. It doesn't matter one bit what gears Lance uses, what I use, or what your local racer/bike mechanic uses.

Once you do that, take an hour to plot out the gearing combinations of all of the equipment options that you've been considering. A little bit of cost/benefit analysis and the question answers itself. Until you figure out what gears you need you're just spending money hopeing to stumble onto the right combination.