Save your $200 for a road bike :-) Seriously. The 7.4 is an awesome bike and you should ride the daylights out of it. You probably want some bar end grips (Ergons?) to provide additional hand positions. I'm a fan of clipless pedals or at least to clips so that you can pedal hard without risking your foot sliding off the pedal. Get a $35 cyclocomputer to track your speed. I like the Cateye wireless. If you want to get faster, you need a good training regimen. Intervals, hills and long rides provide different benefits.

If you are changing cassette and crank and tires and stem, you probably bought the wrong bike.