[Z-man]

TJM:
Like stray said, you can use a Zip100 disk in a Zip250 drive, but the access time (both reads and writes) will be a little slower than if you use a Zip250.

BTW: If you're getting an external Zip drive, I suggest you get the Iomega Zip250 Photoshow drive. It's got RCA & S-Video jacks, which allow you to hook up the Zip disk to a TV, and view JPG pictures via a slide show. You can also view Power-point presentations on it too. Also: you can hook the same device up to a VCR, and add titles to your videos. (Ex: I added my times and still pictures to my autocross videos) Not the most professional, but it's still pretty good.

-Z.