Some "Video Cartridge" questions - can anyone help?

Hi chaps...

A bit of background... my parents have a UK model CDI 220 (not sure of
the full model number, but I'll find out).  After years of it sitting
idle I noticed that Nero has the option of burning MPEG1 CDs and it
automatically writes the CDI directory on them.  Since they haven't
got a DVD player and are largely technophobes, I wondered if I could
aquire them one of the MPEG cartridges and burn avi (DivX) or mpeg
movies off the net for them.  If all the pieces fall into place, this
would be very nice for them indeed.  Hence my questions:

Can DivX films translate to MPEG1 (with Nero, or with some other piece
of software), and will they run on a CDI and usually fit on a disc?

Is there anywhere I could likely buy an MPEG card from on the net?  

Since my first searches at answering the last question drew a big fat
blank, I noticed that US models of the machine go on e-bay pretty
cheaply with the cartridge installed.  Apart from the differences
between the two versions of cartridge that came out (got that sussed),
are there any differences between US and UK/European versions of the
cartridge?  Can I pull the cartridge out of one and slot it in
another?

Many thanks for any help anyone can give me...