how do you change the xbox hard drive and replace the software in the other hard drive?
If Linux is already installed, you’ll have to attach one of the hard drives to the DVD drive cable and basically perform a regular Linux hard drive upgrade. See the HOWTO’s for more info. If you have not installed Linux yet, you’ll have to consider why you need that software – you will not be able to run XBox games with an upgraded hard drive, so you’re probably better off doing a hardware mod and installing Linux on the new hard drive while it’s still empty.