QUOTE (tjcinnamon @ Jul 28 2008, 11:27 AM)

So when a DVD or CD is read in the BIOS is the driver for reading UDF and CDFS contained in the CD drive?
No, the BIOS contain a basic CD driver. A CD drive dosn't know a file system.
There is a Bootable CD Specification
http://en.wikipedia.org/wiki/El_Torito_(CD-ROM_standard)http://www.phoenix.com/NR/rdonlyres/98D321.../specscdrom.pdfDifferent hardware and software manufacturer follow this specification. A CD boot is reliable nowadays.
BIOS and boot CD follow this specification.
A current BIOS should boot a USB CD-ROM too.
However that's not part of Bootable CD Specification, hence it's not supported officially.
The BIOS may boot a fake CD-ROM (U3 CD part). Or the BIOS may fail.
Remember, there is no USB boot specification.
Different manufacturer created different solutions.
One USB stick may boot at one machine, but fail at another machine.
Some BIOS may even boot a UDF or CDFS file system from USB massstorage.
However that's most unlikely. Often a floppy or hard disk is expected at USB massstorage.
QUOTE
I'm trying to find a unified method to boot the install disks of OSX, XP, Vista, and other OS's from a USB drive.
Remember again, there is no USB boot specification.
It is not possible to create a always working USB boot solution.
I doubt, formating UDF or CDFS at USB massstorage gives reliable results.
I suggest: use a hard disk approach at USB massstorage
Or try: UDF or CDFS at fake USB CD-ROM (U3 part)