Yes, but in order to do so, you must partition the drive into at least two partitions. You will need one for the intel and one for the PPC. The two formats are different and neither type computer will boot to the other normally. You will need to install the OS on each partition with the corresponding computer type for its partition. I used an old 40 GB drive set up like this to create myself an emergency boot and utility drive for my Macbook and PPC Macs. I installed Leopard on on partition for the Intels and installed Tiger on the other for the PPCs. I also installed various utilities like TTpro 4, Drive Genious, DiskWarrior, and etc, on it. 3 On Oct 3, 2008, at 2:45 PM, Zane H. Healy wrote: > > Is it possible to install Mac OS X on an external Firewire HD such > that you > can boot either a PPC or an Intel-based Mac? I want to build a new > utility > disk that I can use to boot any of my families Mac's and run various > utilities against them. > > Zane > > _______________________________________________ > X4U mailing list > X4U at listserver.themacintoshguy.com > http://listserver.themacintoshguy.com/mailman/listinfo/x4u > > Seven Cent Deals - Great legacy stuff Great Legacy Price > http://www.drbott.com/prod/db.lasso?cat=Seven+Cent+Deal