I strongly urge you to go to the coolrunnings.com website and look up the Couch to 5K program. With that program, you build short intervals of jogging into your walks, and your body slowly gets used to longer intervals. Before you know it, you're running for 30 minutes straight and after that, the sky's the limit!
I'm sorry, I have no idea what BTDT is, so I can't help you there!
As for knees, if you're worried you may want to check with your doctor before you start. I started when I weighed around 250 and I did have some knee pain because I was carrying that much weight, but I didn't have knee problems before that. And the pain went away very quickly. You weigh much less than that, but if you have other knee problems your doctor would have to advise you. I've been reading lately that running is NOT really bad on your knees, that it actually strengthens your bones and joints, but I don't know for sure.
Lots of people here at 3FC have done the C25K plan. I did sort of my own version of it, and now, less than a year later, I can run 10 miles. I'm training for a half marathon! You should check out the Cool Runners thread -- lots of inspiration there.
Start by doing what's necessary; then do what's possible; and suddenly you are doing the impossible. -- St. Francis of Assisi