Having come from where you are, I feel strongly that the only way to improve your running is to run. Google "Maffetone Method" and check it out. It's a great way to build a base and to get started running while minimizing the risk of injury. It can be very frustrating at first (because you want to go faster) but stick with it.

Enjoy the journey. I was way too fat & out of shape in '04 and worked my way up to a HIM in '06. In '08, I finished IMAZ and this year I've completed 3 HIM's (Oceanside, Hawaii & Austin). NY Marathon this weekend...then my season is finally over.