Jerry,
C25K is a good plan to work up to running three miles. My only advice would be to start slow and get a GREAT pair of running shoes. If you can, go to a running store and have them "measure" you and recommend a pair that is right for your gait, foot type, etc. I didn't do either of those things when I started the C25K and my "reward" was plantar fasciitis!! I am now just starting back to jogging/running a little. I don't think I will ever be able to run three miles straight, but I feel good just pumping it up for a minute or so at a time during workouts. After years and years of smoking (quit over a year ago), my cardiovascular endurance just isn't where it should be.
Good luck!
Carrie