I guess my OP wasn't quite clear enough; what I'm trying to merge are two ISOs; one is just a Win98SE boot disk, the other is the actual Win98SE installation CD. In essence, I'm trying to create a bootable Win98SE CD. I need to do more than just set the "bootable" bit, I need to have an MSDOS/Win98SE bootable disk, with CDROM drivers, etc. All that is what the first ISO has on it.
Admittedly, I shouldn't have to bother with this at all, but I can't get VirtualBox to recognize both the boot CD and the install CD at the same time. However, *that* is not a topic for this forum!!