I just bought a Plextor PX-504A (DVD+R/+RW Only) and i'm experiencing
compatibility problems across Apple DVD-ROM Drives. I use a PC with
the drive i just mention to burn media, but i cannot read them from
any of my Macs: iMac with the 15'' Flat Panel display (no Superdrive,
just DVD-ROM) and an iBook (dual USB port) with no superdrive either.

Problem is my macs won't read the discs at all!.. I'm using Nero
Burning ROM 5.5.10.15 with either DVD+r and DVD+RW media.

The funny thing is that i tried on a PowerBook 12'' with an upgraded
firmware and it worked smoothly. There's no firmware updates for the
other macs i own.

There is a possibility that the DVD-ROM drives in your iMacs, just may
not support the DVD+RW.  However, many compatibility problems arise
from the quality or color of the dye used on the DVD+R/RW media that
you're using.  You may want to try a different brand of media with
your DVD+RW drive.  One last suggestion if all else fails would be to
pull your DVD-ROM drives out of your iMacs and see what the make and
model of the drives are, then go to the website of the manufacture and
see if there's a firmware update for your drives there.