I did my first Duathlon at the weekend too, it was a 4Km run, 10Km off-road ride, 4km run. I finished it in 49 mins 7 secs in ninth place and am really pleased. The cycling was my strength - i didn't see another competitor cycle up all of the hills without jumping off and pushing. The field seemed mainly full of runners who struggled on two wheels, mountain bikers who hadn't done much running and road time trialists who didn't really have the technique to get up muddy hills.
So now i'm preparing myself for my first tri booked for 10th May on the same course, but starting with a 400m pool swim. Rather embarrassingly, i expect my overall time to be slower than the this one (my swimming really is that bad!) but you gotta start somewhere.