I just got around today, to trying to copy some images
onto the built in DVD recorder.

I've got the stuff on my windows XP machine to read a UDF formated dvd, so I'm good there, but all the files on the disk are
files, and there's nothing on the web about this extension
(except about StarOffice) and nothing I can find to
play them.

any thoughts?

If theres nothing executable on the dvd, like a viewer then I guess the software must be elsewhere... Double check there are no files that could be a viewer, if not then did you get a cd with the dvr? If you did, then check that (and in the manual) there could well be a player/viewer for copied content/backups in that software.

Failing that, it may be available as a download from the manu, but I would check the above first.

Also, a long shot, but see if there is a newer version of the firmware available, it may have better handling of the dvd writing to include a viewer.