Plumax makes nice external cdrw enclosure that take USB or firewire connections.
Buy a lite-on (or other internal cd-rw drive) put it in the enclosure and you are set.
It will also cost you a lot less than buying a commercial type one.
www.pcmicrostore.com (search under Plumax models, should be one for about $33-$54)
I bought an internal cd-rw drive... lite-on is a good and affordable brand.
I bought a Cendyne 48x16x20x one.
Installed the drive into the external case and it works like a charm on my win2k and winXp boxes.
My friend who has win98 has to install a driver which comes with the USB external case.
Goodluck,
Mer.