Burning a movie onto DVD-R media does not automatically make it a "DVD". It
must also be in the proper format, which must be done by software designed
to make standard playable DVDs.
Microsoft does not currently offer any products that produce DVDs, though
I'm sure it must be coming, since creating DVDs is starting to become
commonplace. In the meantime, a third-party tool is the best way to go.
Many are available, both online and in retail stores. They are not
expensive.
As for the video not being playable on your computer, the internal video
format (or "codec") must be a format that is not recognizable by your
system. Check the source of your video, determine the format, and download
or purchase the proper codec. If it's MPEG-2 you may want to get a DVD
Decoder Pack if the DVD creation software you get does not improve the
situation. These are available at:
http://www.microsoft.com/windows/windowsmedia/windowsxp/buypacks.aspx
My column on DVD playback may also be of help.
http://www.microsoft.com/windowsxp/expertzone/columns/bridgman/02april15.asp
Regards,
Galan Bridgman
Microsoft MVP - Windows XP Digital Media
Expert Zone Columnist