Thanks for all your replies - much appreciated
Eric - I will definitely keep doing shorter and longer races - there's a 5k series right near me, on first Sunday of every month that I will do.
Sasha - I think I will do that and wait till I can run 1:25, I kinda see what you mean about training then race, I will give it some thought.
Nathan - Yeah, I think long term it is better to keep up consistently logging miles, and I'm planning to continue doing this. Plus hopefully in 2010 by the time I run a marathon my endurance will be much better so I can run a marathon time closer to what my half would predict.
Thanks everyone