A 1000 watt power supply doesn't use any more power than a smaller sized unit. It has the potential or ability to generate a 1000 watts, but it is only producing enough to meet the demands of the system. If my system needs 850 watts then the 1000 watt power supply generates 850 watts, not 1000.
Think of it like this. Your house is connected to the power lines and they have 1000's upon 1000's watts of power. But your house only takes what it needs. Now they upgrade the Power Plant and it has the ability to produce twice as much power as it did before. Your house still only takes what it needs.
I'll be running 3DMark06 later, I'll keep you updated
Edit: 3DMark06 in WinXP 64 - 25018 -
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3DMark06 - Windows7 64 - 24871 -
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