How to create a dvd that is playable on external player?

I am running windows xp media edition, I have a dvd burner drive. I can create dvds of my projects fine. They playback fine with sound and video on a computer. They will not play on a dvd player. Do I need another software program or can this problem be worked around? I use WMM and WMP for most projects. If software is the solution, I open to suggestions. Simple if possible.