Watched some of 24 (Season 6) this morning and the time flew by. Leg felt fine. I played the "adjust the speed by .1mph every minute" game today.
So, I was reading online yesterday to see if there was some definite difference between the effort of running on a treadmill and running on the road. I got some interesting results. Most people say that to make it comparable you need to put the incline on 1-2 % to counter the lack of wind resistance. I also saw one site that states that you should add .1 to .2 mph rather than the incline trick. Then there was one site here that says that unless you are running 5:22 a mile or faster on the road, the wind resistance is not sufficient enough to make a difference. Very interesting reading. Personally, I tend to agree with the last site, where unless you are running very fast, the difference is minimal.
There is another major difference in treadmill vs road in that when your foot strikes the treadmill, the action of the belt forces a quicker heel to toe plant causing more of a "slap". I don't think this affects the speed, but it can potentially change the biomechanics of the runner. It can also lead to shin splints and other injuries due to the differences.
Food for thought...