xbox 360 flashing hitachi problem

I have a Hitachi 78fk and i was trying to flash the firmware. First time flashing so I dont rly understand much yet. So i had my xbox hooked up to my desktop via SATA and I was all set to flash it then i couldnt get it into mode b. I had my xbox on and turned my computer on with the slax discs in it and it booted it up. But before it got to the spinning up disc message or w/e it said FATAL ERROR or somethin like a that and restart your computer with CTRL+ALT+DEL and so on. I've tried using different slax discs thats not the problem I tried resetting everything and plugging and unplugging the SATA cables. Im guessing the problem is with my desktop, I'm using a dell inspiron 530s with Vista 64 I think. Anyways thanks for any help:).