Its called the Couch to 5K program. It's a program that will get you from no running what-so-ever (hence the couch part) to running a 5k in 9 weeks. I also have podcasts that do the interval training with music, so it tells you when to switch from walking to running and stuff. Its actually quite fun and doesn't work you too hard, but enough to get you used to the idea of running.
http://www.coolrunning.com/engine/2/2_3/181.shtml 