if you dont have nero, get the 30-day trial at www.nero.com, once you have it, select DVD, then Photo and Video, then Make a DVD Movie. From there you can import video files (the file that you make with movie maker) it encodes it, and burns it. You can even add a menu and stuff if you would like.
An easier solution is to open up the file with Windows Media Player, then add to the burn list. When you burn the dvd, it will automatically convert the file.
An easier solution is to open up the file with Windows Media Player, then add to the burn list. When you burn the dvd, it will automatically convert the file.