i plugged in the 30 gig master drive alone and it booted up fine.

Good. That rules out a dry solder joint on the mainboard, and rules out a mis-plugged cable.

i then removed the slave jumper from the 18 gig and tried that one alone and got the same 'disk not found' error so i guess we have found the culprit.

Did you plug it into the same spot on the cable as the 30-gig drive was when it worked? If so, I would agree that the 18 gig drive is now suspect.

How do i get a boot log? Hyperterminal?

Complete instructions are here. Do it with the good drive in place so you can see what it's supposed to look like when it boots from a good drive. Then try it with the suspected-bad drive in place and see what's different about the boot log.

Was the 18 gig drive ever properly "built" using the builder-image?