emulatorII-list

Strange that your seller would disappear before telling you what you were buying and how to use it..?

.nrg is a Nero CD image (Nero is CD writing program for PC).
.toast is a Toast CD image (Toast is a CD writing program for Mac).

If you want to see what these are about, you may have to use these files to burn CDs (instead of trying to mount the files directly). After burning these images to CD-R media however, you may find that the created CDs are in OMI CDS3 format and still unreadable by your Apple CD300. In this case Id bet that your working unzipped files with the .EII extension are the very same files located in the .nrg and .toast CD images, and you were just given duplicate copies in the original OMI CDS3 format.

If you have further questions about converting/burning CD images (off topic for this group), I can try to point you in the right direction if you email me off-list.