Most people don't realize that you can create a bootable NT 4.0 floppy, but it can be a life saver if you ever wipe out your boot menu or MBR by mistake.
To create the floppy, log-in to NT and insert a blank or expendable diskette into drive A:. Right-click the floppy disk icon in My Computer or Explorer and choose "Format." Format the disk: every disk you format with NT is bootable, by the way, you don't have to copy any system files or manually make it bootable in any way.
Now, copy the files NTLDR, BOOT.INI, and NTDETECT.COM from the root directory of your startup drive onto the floppy and you've created a bootable NT system floppy. Reboot your computer to test it: you should get the same startup menu you get when you boot normally.
Keep the floppy in a safe place--it will come in handy some day.
Thanks to Brian Kelley for the tip