@ Wilse
As Downix said, try moving the CD-ROM; try different configurations of Master/Slave, try to set it manually by jumpers and not rely on "cable selection", try to have both the harddrive and CD-Rom on the same channel, try the opposite, try different channels, etc. Ultimately, try another CD-ROM. If it still doesn't work, I would go back to the store and ask for another kind of memory.
I hope you get your Pegasos working soon! Let us know when you are surfing from Voyager or Ibrowse! :-)