I agree with everyone about the trailer- it's amazing how little drag you feel with it, you don't even know it's back there. My boy can sit in there with a sippy cup and a couple of toys and either play or watch the scenery.
About three months ago I got sick of getting fatter and fatter every day and ordered nutrisystem. I've lost 30 pounds in three months- many more to go but at least I'm going in the right direction! About three weeks ago I got a folding bike, and have been riding every day ever since. I keep it in my car and ride every day at lunch, riding hills for about 45 minutes. On the weekend I go to the park and try to ride 6-10 miles. I'm addicted and it's great exercise. I started on the elliptical three months ago, but since I've been riding the bike the elliptical doesn't get much work. I'm sure once winter sets in, though, it will see more action.
Get a bike that fits you and is comfortable, no matter what kind, so that it's fun to ride. I see bike trailers on craigslist now and then, and yard sales have them really cheap sometimes.
good luck!
vickie