I found this in a few different places around the 'net - hopefully it's helpful:

Create an MS-DOS Startup Disk

You can easily create a bootable floppy disk by following these steps:

• Place a blank disk in the floppy disk drive.
• Click Start, and then click My Computer.
• Right-click the floppy disk drive, and then click Format on the shortcut menu.
• Click Create an MS?DOS startup disk, and then click Start. Now you're on your way to a bootable startup disk.

Note: The MS-DOS startup disk only allows the system to boot into an MS-DOS prompt. The disk contains no additional tools.