I updated to the CFW with the same USB I'm trying to use to get back to OFW but it doesn't work i have tried it many times. I know what to do Make a ps3 folder in caps then inside that make an update folder and download this update http://ie.playstation.com/ps3/suppor...28ver-3-55%29/
and put in the folder same process as the CFW. As anyone actual done it rather then saying it can be done
just back up files you want and system restore
Why exactly would you want to?
Doggz is right if you do not know how to format
Go to start, computer, Right click your usb then format, make sure you put Fat32 or else it wont work =D