As Mattk has already mentioned, Nero will do the conversion for you, but it can take several hours.If you want the process speeded up, I suggest you use a program called Win AVI, which will convert a movie to DVD format in about 20-30 minutes.Nero then does not need to do the conversion and you will be able to burn a movie to DVD in about 15 minutes.
To burn a video to DVD using Nero is really easy.When you open up Nero StartSmart there is a drop down menu at the top where you can select CD or DVD.Once you have slected DVD, you then need to select the 'Make your own DVD Video' icon, which can be found when you click on the gold star icon.You will then be taken to another screen with some selections on the right,select 'add video files'.A box will appear where you can search for your video file, double click on the file you want, and it will load into Nero ready for burning.All you do now is click the next button until it changes to the burn button,and then click on burn.You video should now burn to DVD.