The problem with running a QT off a laptap is that it’s a pretty large size file, it may stutter. I don’t like presuming anything, but it sounds like you may not know DVD authoring, if you do then I apologize. A looping DVD is very easy to create if you have a program to do that.
What I think would be the easiest and will play on almost anything would be to render the movie out with a MPEG2 compression. Under the format options on lossless, I would create 2 or 3 compressions, with different target bitrates. Just in case the laptap has trouble playing the movie.
Have the client play the video in windows media viewer, set it to full screen and repeat.
Just my .02 cents
Good Luck
johnny