My ultimate goal is to have a single DVD that can multi-boot into all the useful tools I can cram into it.

It's a lot easier to learn to build multi-boot systems on a USB hard drive (or even a USB thumb drive, but they don't usually have enough space). If you try to learn on CDs, you'll create 100+ coasters. So learn on USB drives first, then transfer your setup to CD afterwards.

My current setup will be:

• DVD is in no-emulation mode, and the main booter will be GRUB4DOS.
• You can choose to boot into MS-DOS, where there will be Ghost/PartMagic/etc etc
  • if it were possible to use GRUB for the entire menu system, rather than doing a GRUB+config.sys hybrid, that might be useful, though it would require some hacking
• swiss army knives
  • Hiren's
  • Ultimate Boot CD
• bunch of portable apps that can be used from Windows
  • Hiren's contains a few
  • PortableApps
• live Linux — Knoppix CD, AND BackTrack
  (if building a CD, use Puppy Linux instead)
• live Windows
  • UBCD4Win?
  • LiveXP