It does not matter really, but you do want the ROM as the primary and writer as the slave, just so if you go into bios to make the boot first the rom (bootable dvd) it uses the fastest loading drive, writers to note run live as fast, so I would recomend the rom
But again, its not important either way, unless you think like me
And so yes firestorm you can not boot from a slave dvd/cd drive, only the primary.