Reformat and Install Tutorial? Tutorial, Install, Reformat

john

I have an original Xbox that, some time ago, was hard-modded and had a 300Gb HDD installed.  There've been some problems with it (the partitions being too large and things disappearing) and I really just want to reformat the whole thing and reinstall XBMC and start over.

Is there a tutorial anywhere that will walk me through doing this?  I've done a lot of googling and I've had no luck.  I figured some real-live humans might be able to help.