Dumb training question

Being new to the sport, I am trying to understand the ultimate goal in training.  I guess this goes along with the question "How do you know you are ready?"  I know the obvious answer is to build endurance and strength to not get injured.  I am training for Augusta 70.3 in Sept. 09 with an oly and sprint between.  I have only taken training seriously for about 5 weeks.  I am a swimmer and moutain biker, but certainly not a runner.  At this point in my training, I feel I am pretty far along.  I can swim 2K without stopping in under 40 minutes.  I am making the transition from mountain bike to road bike (I am getting my bike fitted for me today) and I can run approximately 7 miles at a 10 minute / mile pace.  Again, I am not a runner.  I can do some small bricks without any trouble (20 mile bike, 2 mile run).  My plan is to continue to build miles eventually following a training plan.  I love the training.  I can't wait to get in the pool, on the bike, or on the road every day.  I am I heading in the right direction?