Actually, as long as the low-level boot driver (i think it's in open firmware) can use the DVD drive as a boot device (unless you upgraded to a superdrive or something yourself) it should be possible to boot from a DVD. (I'm pretty sure it's possible, because the driver is independent of media type; it is the drive mechanism that matters to the driver)
Also, DVDs don't have to be in some kind of "DVD-format." They can be in HFS+ format, FAT32 format, DVD-Video format - basically any popular format like that. Hell, they can even be in UFS format!
Obviously, they can't be in an Audio CD format or VCD or anything CD-exclusive, but they can technically be in pretty much everything else!
and by the way, Happy Birthday! buy yourself an iPod!
(unless of course you lied on your macosx.com registration page, but you wouldn't do that because it's horribly immoral, right?
)