Hi Doug,
Well the answer depends on how the files are on the DVD disks.
If they are simply video files burned to the DVD disks as data then simply
copying them to your harddrive and importing them into a DVD Authoring
program will do the trick.
If they are, and I assume this is the case, "proper" DVD disks (meaning the
files on the disks are actually VOB files) then the process is a little more
difficult.
There are a number of programs out there that can "rip" the video files off
the DVD and convert them to a format Movie Maker can use such as:
Nero: http://ww2.nero.com/us/index.html
TMPGenc: http://www.tmpgenc.net/
Super DVD Ripper: http://www.dvdtodivx.net/
Or do a google search for "DVD Ripping"
Check out this site for more information on converting VOB files: http://www.videohelp.com/convert
Hope that helps.