Why does the preview of my DVD not play smoothly?
The preview in Windows DVD Maker is designed to give you an idea of how your menu and video settings will look when you play your DVD, but sometimes a preview may appear choppy or slow, even if all of the files in your project are undamaged. It is important to note that the quality you see in the preview does not predict the quality of your final DVD because the quality of the preview depends partly on the speed of your computer processor and the capabilities of your video card, while these factors do not affect the video quality of your burned DVD. If your preview is not playing smoothly, you can try closing other programs to free up system resources on your computer. You can also burn a test DVD to make sure everything appears the way you intend it to.
Note: This information provided by Microsoft.