Found a great pdf on how to flash your 360 and worked a treat for me
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Sata Chipset needed:
Samsung MS25: Most will work (VIA and NForce 3/4 best). SIL, Promise and NForce2 DO NOT WORK.
Samsung MS28: VIA work best. Especially "VIA VT 6421" series.
Hitachi 46/47/59: Pretty much everything works. So these are the best, you for sure don't have to buy anything
Hitachi 0078FK: Pretty much everything works except SIL chipsets which DO NOT.
BenQ: VIA or NForce SATA chipsets work best.
I used a VIA VT6421A PCI Sata card. It also has 3 ports, but only one of them will detect the 360 and that is the bottom one (opposite end to the port thats external when installed
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