The rear wheel on the Specialized Dolce Elite needs to be replaced and I am trying to figure out what to get. The old wheelset is an Alex AS1, which is what came with the bike, and which I believe is a lower end model. MY LBS has suggested a Shimano 105 hub and Mavic rim which he tells me will run about $300 for both wheels. So I have a few questions: The front wheel still works so should I just replace the back wheel? My initial research tells me that upgrading my wheelset is one of the first ways to upgrade a bike. But I'm not clear on what the advantages are and what I should be looking for. I am short (5'2") but heavy (210 lbs). Hoping to reduce the weight but that will take a while. I'd really love to get a better wheelset that would help me get up the hills, but it needs to be something appropriate for my size. I probably want to stay w/in the $350 range. The whole bike only cost me about $1400 so it doesn't seem to make sense to spend a lot of money on new wheels.

Can you give me any advice? Thanks!