Emergency boot disk:
These are often created by anti-virus or backup utilities to aid in repairing your system should a virus or a drive crash cause problems.
You might need to use this disk should your PC be infected by a virus, or the hard drive crashes.
Boot disk.
This is ANY disk with the 'system' files on it and the flag in the file master boot record set to allow the BIOS to recognize that the disk is bootable.
Your primary hard drive is a bootable volume.
Many CD-ROMs are bootable.
You use this type of disk when you do NOT want to boot into Windows.
Most often for running a BIOS update.
A startup disk is a special boot disk that loads the files required by Windows to configure your hard disk and begin installing Windows.
You typically only use the startup disk when you are installing Windows for the first time, or when you desire to perform a clean installation.
You can create a bootable floppy by right clicking on the floppy drive, select format, and check the box to copy system files / make bootable.
You can create a startup disk by going to add / remove programs, click on the startup disk tab, and follow the instructions.
Chas