Well it's pretty much a given that the best piece of advice anyone will tell you when purchasing a bike is to not get one of the bikes from a store like Walmart, Kmart, Target, The Sports Authority, ect. If you get a bike, and you want to make sure it's quality, get one from your local bike shop. The brand I'd reconmend to anyone is Trek. Trek is the company Lance Armstrong rides for, and the bikes I've used in the past, I've been really happy with. This past year my dad won a
Trek XO-1, since he doesn't ride much if at all, I've logged about 1,250 or so miles on it. The greatest thing about it is it's designed to be a
Cyclocross bike, so it's a very good Hybrid of a Road and Off-Road, it's lightweight, and rugged. The only thing thats wrong about it, is the fact that it's suggested price is $1319.99
Specialized, Cannondale, Fuji, Giant, and Klein are 4 other bike brands that I'd reconmend.
Don't forget the helmet.