to avoid asking you the console when you attach the hhd the update you must make the update ..
here is two things you must know
1 do not make the 9199 update this update they will destroy your console .
2 make soure you are downloading the 8955 update you can take it from here http://www.megaupload.com/?d=3DLZ9Y7H
format one usb flash in fat 32 format and put the $SystemUpdate file in the root of the flash and just plug in the flash to the console .
when the console ask for update say yes and complete the update ..
this we call avatar update and nothing bad will hapent ....
just be soure to take the 8955 update nothing elese ....