Actually, 100MB is a bit small. Here's why. When you install an OS like NT or 2000 over CD or network it's slow. I tend to take 5 min to copy it to the harddrive (I use smartdrv to speed up the copying). Then I can install. With NT, this makes the full install about 15 min. Much speedier. And since I often don't have a partition created yet (and since DOS, by default, cannot read NTFS) I put it in the DOS partition to be later deleted.

As for having multiple network OSes, if I'm mucking about in security, trying different tools and such, sometimes 2000 just doesn't do it for me. I might decide to use Win98 for something or DOS in some cases (there is one really nifty tool that I add to DOS that I like).

Lastly, the more OSes you are familar with the more you'll be able to comprehend what happens to your users and your environment. I play around with Linux (Red Hat for intel and Yellow Dog for PowerPC), Unix (Solaris), Novell, DOS, Windows 95/98, NT, 2000 and Mac OS (haven't got OS X yet installed but that will come).

Be knowledgable. Be a sponge. Take it all in.

One last thing: this setup I suggested isnt something I'd use in production. I use this for muck around machines, which is the impression I got from Rogue that he wanted. If it was a production machine, there'd be no DOS partition. Heck, the keyboard, mouse, monitor and floppy would be gone.