The best thing to do is to find a good bike shop, and get their advice. Look for one that has atleast 2 or 3 big brands such as Trek, Specialized, GT. Or if they don't have a couple brands, at least cross shop a different store. The important thing is to find a bike that is the right type for the riding you will do and especially the right size.

This is a pretty good time of year to be buying a bike if you are looking for a deal - the remaining 2000 year bikes should be discounted a bit. Don't forget to leave room in your budget if accessories such as helmet, short, shoes, a bag, some tools, water bottle or water backpack... Probably with a budget of $1k, 2 or 3 hundred will end up going into accessories.

Have fun.