First off, I applaud your attitude. Deciding to go from not riding to suddenly riding 10 hilly miles in to work is quite a bite.....and with that, I am going to stress a bit of caution. Before you set that cart in front of the horse, you might consider taking a few test rides, and then when you make a selection do some build up rides. Going from nothing to 10 miles (or 20?) a day is a great way to injure your knees and cause some undue stress to your back, neck, backside.
Follow through as if you do you will be amazed at how much better you will feel...in the meantime take it easy with the ramp up of that plan so you don't get hurt and discouraged. My first ride back was around a mile and I thought I was going to die.