If you want to upgrade your bicycle wheels you would want it to be more aerodynamic, stiffer, and that will roll better than your stock bicycle wheels. This will give you more speed, and the power transfer will be more efficient. It will also give you a faster climb.
Here are some great wheels for your bicycle:
Fulcrum Racing 5 Wheels - it is lightweigh at 1,600g a pair and very comfortable to ride. Watch out it can be a little noisy.
Mavic Ksyrium Elite Clincher Wheelset - This set is light, stiff and has an amazing design. It is the ultimate upgrade wheelset. It has a a new U-shaped profile, with a wide 17mm rim. A pair of this wheelset without tires is at 1550g.