You can simply drop the file into iTunes if is a single movie file otherwise you may need to convert it to iPad format. You can find some good free ones on the net
I havent been able to just drag movies to the ipad. do this, if the moivie is already in Itunes, connect your Ipad to you PC click on the Ipad (in Itunes) and go to the movies tab and check the box next to the movie and sync your ipad, the movie will be on you Ipad
Mike, Sounds like all good advice that has already been given.
If you are still stuck, please see this previous thread. See specifically #2 post ( by Poser) and #$ post (by Twerppoet). Their comments were very helpful. Disregard the "title for updating to 4.35.)--look at the posts assigned. It may be helpful for you.