Easy.
1) Format a floppy disk in Windows 2000
2) Copy your boot.ini, NTDETECT.COM, and ntldr files to the floppy
3) Boot PC from floppy
This will only boot you into Windows 2000. It is a good idea to make this disk in the event your MBR or boot.ini gets corrupt. If the original question of this post was to make a DOS boot disk, go to a Windows 9x PC and create one. This can't be done in Windows 2000 as this is not a DOS based OS.
[This message has been edited by ghachey (edited 22 September 2000).]