DOS formatted zip disks don't mount


dos formatted zip disks on a usb zip drive don't mount on the OSX desktop (or in a finder window) . Mac disks are okay. Does anyone have any suggestions?
I have a similar problem with a DOS formatted FireWire drive. I wonder if perhaps MacOS X is just picky about recognizing DOS-formatted media. I can't find any sign of File Exchange, but DOS floppies work...
When A miracle happened on first boot of X my Apple SCSI PCI card worked, and my ZIp drive on that SCSI chain mounted my PC zip disk just fine, this is very strange. But If you look in the machelp files of Mac OS X (under the help menu) it mentions along the bottom of one of the pages that ANY MO on USB shouldn't work at all...that reminds me, this is Mac OS X FINAL...right?