No more fsx on windows vista

I have officially had enough. After buying all my new equipment installing everything for the past several days and just about getting things where I like them my simulator is not responding when I start it up and after 20 to 30 seconds I get a message saying A fatal error has occurred. Everything else is working top notch and wicked fast. I wont put up with this BS operating system anymore >:(
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I am taking vista out and putting XP 64 bit back in, my vista disc will now find a nice new home preventing stains on my coffe table as a very shiny coaster. My question is will I have to do anything in my fsx config to take advantage of the quad cores on my processor or is that already taken care of by service pack 2. I just want to make sure that I am not going to be limiting my new hardware by going back to XP. The only thing that has changed since I installed the OS is I replaced the QX9650 I picked up originally with a QX9770. Any help is welcome
My specs
Intel Qx9770 3.2ghz quad core processor
Asus maximus extreme motherboard
8 gigs reaperx dual channel pc 10666 ddr3 memory @ 1333 mhz
EVGA 9800 GX2 1gb ddr3 graphics card
Seagate barracuda 1 terabyte hard drive
Ultra X3 1600 watt power supply
Coolermaster cosmos full tower case
Liquid cooling throughout.
Vista Ultimate 64 bit(Do youself a favor dont buy this pile of garbage)

I am taking vista out and putting XP 64 bit back in, my vista disc will now find a nice new home preventing stains on my coffe table as a very shiny coaster. My question is will I have to do anything in my fsx config to take advantage of the quad cores on my processor or is that already taken care of by service pack 2. I just want to make sure that I am not going to be limiting my new hardware by going back to XP. The only thing that has changed since I installed the OS is I replaced the QX9650 I picked up originally with a QX9770. Any help is welcome
My specs
Intel Qx9770 3.2ghz quad core processor
Asus maximus extreme motherboard
8 gigs reaperx dual channel pc 10666 ddr3 memory @ 1333 mhz
EVGA 9800 GX2 1gb ddr3 graphics card
Seagate barracuda 1 terabyte hard drive
Ultra X3 1600 watt power supply
Coolermaster cosmos full tower case
Liquid cooling throughout.
Vista Ultimate 64 bit(Do youself a favor dont buy this pile of garbage)