just ftp over c/ and E/ folder do the lot to be safe not D/ its your dvd drive to you pc in a folder call it xbox H/D burn it to cd-r for safe keeping
then if you got slayer evox installer place new hard drive in and place slayer in dvd tray reboot xbox do a new install upgrade harddrive and your done the slayer will do a rebuild of you xbox and put on ms dash as well as evox dash if you wont a another dash like XBMC you can try auto installer delux 2 dvd and do it with that and pick the dash and apps you wish to install
update your bios before you do this if you are runing old bios
x2 5035 is the laters bios for x2 chips