i'm going to guess the brakes are probably tektro?

most likely they are pretty good, i would replace the pads with some kool stops or swiss stops and be done with it. i have replaced the pads on every bike i've ever ridden, stock pads are usually lacking, and for the relatively low price of new pads - they will make the biggest difference in braking capability of the bike.

now if you just want to upgrade for the sake of upgrading, go right to dura ace.