What are you trying to do? When you post a question, including a LITTLE more info than "wont work" is always nice, since no one here is a mind reader.
You might want to look here: http://home.alltel.net/nghtshd/xbtool.html#Supported
It would be mighty silly if you were actually trying to change something in a retail bios.. (ie: the open button)
If you are trying to resize the bios, use the "Resize" button, if you are trying to unpack the bios, you need the rc4 key for the bios that you are trying to use (either 1.0 or 1.1)