I think you will find commuting via bicycle far more rewarding than you imagined. Trading in my hour-plus commute each way everyday, getting bent out of shape while during in traffic listening to crappy for a couple miles of riding and reading on the train and/or bus in between was a no-brainer for me. I just wish I had made the switch sooner.
As far as a bike, get something that fits, and is in decent shape mechanically. Get some lights. If you plan on riding when the weather is less than suitable, fenders are nice. I like what tjspiel had to say about handlebars
...as far as Urban traffic goes, I like narrower bars and the ability to keep pace with traffic. That's easier with a more aggressive riding position and I don't feel I give up much (if anything really) in terms of being able to see what's around me.
Kryptonite makes great locks. They're pricey, but if you've ever had a bike stolen you probably regret not buying a more sturdy lock.
I don't know how densely populated an area you live in, but riding in large metropolitan areas can be nerve racking at first. It took me a couple weeks to get used to keeping my head on a swivel.