Mark,

Unless you have extremely steep hills, most any bike will get you 5 1/2 miles. If your budget is really cramped, look around at used bicycles. My current commuter is a 20 year old rigid-frame mountain bike that was free, but I have added fenders, street slicks, a package rack and lights. It's been a very sturdy bike. It allowed me to pay off $20K of credit card debt in 2 years, and apparently just in time considering the state of the economy.

Special clothes will depend on your weather. Check out the winter riding forum for info for that. But generally you will be able to ride in the clothes you have, though I'd recommend some better gloves and a good knit watch cap and some lip balm. Also get a rain suit if you don't have one. Winter rain can be the biggest challenge to a newbie commuter.

I know that you will succeed. You have the greatest motivator... no choice. But you will find that you gain some wonderful things in bike commuting. You will be more aware than your motorized roadmates. Sunrise, sunsets, animals and flowers by the side of the road, flocks of geese overhead. The motorists miss it all.

It may seem like a strain now, but give it a little time. For me, continuing to ride has been perhaps the single best decision I have made in my life.