HackMii NAND backup

I soft modded my Wii today, using letterbomb. I followed the instructions from this website, and in doing so also installed HackMii or BootMii, whatever it's called and performed the NAND backup to my SD card. I really don't understand what this does other than provide a safe backup of my Wii in case I need to restore or something? I don't know, I'm just wondering if I really need to keep this backup on my SD card. Seems like kind of a waste of the SD card to me... ?

You can move the file to your computer if you want. The NAND backup is just that, a safe backup of the Wiis state that you can restore to if something damages the software on the Wii.

.. Moving to computer.. good thought. Why didn't I think of that, durr. Thanks :) Well hopefully I never have to use it!