My Windows Vista re-installation DVD wont load up when i insert it.. Help, please!?

i'm trying to clear everything off of my laptop, and reinstall everything, so it will be faster. but when i insert the CD it acts like its going to load up, but then it stops. and when i go to My Computer and doubleclick the CD drive, it doesnt do anything.. i'm computer literate, but please list the steps, because i am still learning. :D