treadmill training

Question
Hello,
I have already gotten a lot of information from questions you have previously answered.  Thankyou!  I am training for a 1/2 marathon in April.  Due to the current weather in Denver and having two little children, I am unable to get outside for running.  So, I get up early and run on my treadmill.  I am currently running 4-5 miles five times a week.  Is training on a treadmill going to put me at a disadvantage?  Should I add incline to mimick what the race course will be like?  The course only has one incline for 1/2mile.
Also, how many miles do I need to run in one stretch to know that I will be able to finish the race?  Ten?
I am 31, weigh 112, run 6.0-6.5 mph. I am hoping to finish in 2 1/2 hours.
Thank you so much for your help and knowledge.
Breah Hooper

Answer
Hi Breah
Regards the treadmill,you have to do what you have to do untill the weather becomes tolerable for a run out side.You could add a little incline a couple a days a week to work the quads a little.The most important run for a half is the long run in which i would try to work up to two hours once every 10 to 14 days.I think if you keep up with what your doing and get outside when you can and add that long run you will be the hero of your own success story come april.Any other questions just get in touch.

All the best and
success

John