I recently bought a new xbox and transfered my old hdd and mod chip(not sure what it is but i beleive its and xecuter that just screws in) a very old version and it lights up green but the system gives me a ms error screen 05 i know the xbox works. What i cant figure out is what i need to do besides just swapping my guts with the new box?? Do i need to flash it somehow or lock it and if so how if i cant access the OS and will i lose all i have on my drive if its flashed?

Since you have a chip installed, assuming solderless, you need to boot the X2 bios, and not retail (which seems to be happening) and re-lock it from there if you plan on booting retail bios, but now there really is no point since XBL has been discontinued on the original xbox and titles. If you are unable to boot the X2 bios by normal means, you can always ground the D0 point (the small wire you needed to place in the trace) and that will force the chip to boot. (also make sure that your D0 point is installed properly in the first place, could be the root of your issue..)

5 - kernel - HDD not locked (The retail xbox bioses require the hd to be locked)
http://forums.afterdawn.com/thread_view.cfm/210562

Hope this helps..

JEB