I did couch to 5K with Robert, starting in July last year.
In April 2009 I weighed 11 stone. I bought a rebounder and went on it at home three times a week, while at the same time starting to lose some of the weight by calory counting and using www.foodfocus.co.uk
Once I had lost a few pounds and was starting to feel less self-conscious, I started Couch25K and finished it in mid-September. I carried on running, aiming to run 5K each time instead of the 30 minutes of the pod cast, which gradually brought my 5K time down.
Before the snow (I can't believe how frustrated I was at not being able to run for nearly two weeks!) my PB for 5K was 30mins 50 seconds, but average closer to 32.
I aim to run three times a week: two shorter runs of 5K, and I'm now doing a longer run each Sunday to stretch me gradually to 10K by the end of March. I've managed 7.5 so far, and I am now just over 9.5 stone and for the first time in my adult life am within sight of a normal BMI.
Go for it. Don't look at what you ran last week, look at last month. Don't worry about repeating weeks, or some days being not as good as others.
I was crap at sport at school and never in my wildest dreams ever saw myself as a runner. But I am, and it's damn empowering! Good luck.
PS If anyone seems you in the street, remember that they don't know that you have in fact only just been running for 90 seconds and not 90 miles! So don't worry. Everyone out there (IME) is friendly and supportive.