I'm not going to reinvent the wheel here, but many of the people who've answered my survey have asked about advice on buying bikes and equipment.
Anything I could tell you has already been said, so here are a few non-commercial, unbiased sites that will help you get started. I've added these to the blogroll, below, but I made a post out of this so you would see it.
Good luck! The only advice I'm going to give you about selecting a bike is just do it. Don't waste your life analyzing everything down to perfection when you could be out there riding. A bike that's 75% perfect will be fine for most riders, msot of the time. Go for it!