Because Mac OS X is not compatible with the PCMCIA decoder cards those PowerBooks required. I am hoping there is no surprises with the Pismo's on-board DVD decoding ability.
Yeah, you shouldn't have any problems at all doing that. The Pismo didn't use the decoder card the earlier models did - it uses the processor to play DVD's. Both the 400MHz and 500MHz versions of the Pismo played DVD's just fine.
In fact, my sister-in-law uses my old Pismo for just that purpose (and email/web/MS Word).
I've got a Pioneer SuperDrive in my 550Mhz G4 Pismo, 1Gig RAM, 120Gig Seagate 5400 RPM HD under 10.3.9 and it has always played DVD's without a prob, full screen.
Seven year old machine that runs with the big boys! 🙂