I agree go with the Couch25k program! Its an awesome intro to running and you it will actually take you right up to your 5k you have planned as its a 9 week program! I would definatley look into the podcasts for it, I find it so much easier for them to tell me when to run and walk rather than looking at a watch. Robert Ulleys are the ones I used.
I am on week 6 and really love it! I am planning on going straight into the next program (one hour runner) so I can do a 10k in May
I actually finished c25k last year but didnt have a goal after I was done so just let it slip so goals are good