I suggest firstly you try them on your PC - do the files play OK in Windows Media Player? Assuming they do work (otherwise the problem is more complicated) then download a version of TMPG Encoder (a quick look suggest that
http://www.digital-digest.com/dvd/do...s/tmpgenc.html may point you in the right direction). Then use the Project Wizard to re-encode the files in either NTSC or PAL. Then reburn (preferrably using an appropriate wizard in a programme like Nero 5.5) the project to a 80 minute CD-R - this will automatically create the file structure for a VCD.
It's probably violation of one of the above that is the reason for it not playing. If you do all this then you should be able to get it in a playable form.
You may want to check out:
http://forum.digital-digest.com/
They have several forums devoted to VCD so you may find it more helpful to get specific advice there.