Q9550 and lots of problems

Ok i'm going crazy ... i've spent god knows how many hours trying to assemble a system using a Q9550 CPU.

I've tested completely different sets of hardware with the same CPU and no luck. I put a Celeron or Core2Duo in and everything is fine.

These are the configurations i've tested with the 2 different Q9550 CPU's i have:
Board: P5Q-E, P5Q Deluxe, P5K Deluxe
Memory: Kingston 667, Corsair 1066 (512MB, 1GB, 2GB single and dual channel)
HD: WD 500, WD80, Seagate ...
DVDRW: Sony, LG ...
Video cards: Asus EN9500, EAX300, ...
Power supply: Antec EA500, FSP Kingcraft 1000W (with 8pin)

i've tried increasing the CPU Voltage, underclocking, overclocking. All i want is for the system to work. I don't want to overclock; i've tried every bios release on all these 3 boards. Both XP and Vista crash at different points. Vista is extremely slow at the beginning to show the Install button and move on. XP is ok at the beginning but then crashes half way. Both OS's crash at different points of installation; sometimes the screen goes all black, sometimes error messages come such as unable to read source files or different error codes.

The only successful test was with a P5K-VM which was running an old bios; a msg came that the cpu is not supported. I bypassed, installed vista, drivers and everything worked fine.

I'm going nuts ... any ideas guys?