If you're gonna use it only for a Laptop, and expect
to use it for more than the occasional backup, I'd recommend
getting a PCMCIA SCSI adaptor and using an external SCSI drive.
If not, you're going to be limited to USB speeds, which means
maximum 4x writes and lots of cpu overhead to boot...
If you're only going to use it occasionally as a backup device,
then you can probably live with a maximum 4x burn (and inability
to do anything else while burning), and then why not?
Of course, the SCSI adaptor route also provides you with other
possibilities with respect to SCSI devices...
If you're going to use it on a desktop PC, I would DEFINITELY
go with SCSI. You can get a SCSI card/drive for around $200 or
less if you look around--the same price as a USB drive. And you'll
get better speed and lower CPU utilization.
Unless this is for what I call a "granma", that is, someone whose
eyes would glaze over if you tried to explain what a SCSI card
is and how you need to open their computer to install it. In that
case, buy a USB device for (your own) peace of mind.
Kwad