The P5QL will require a BIOS update to be able to use the XMS2 RAM, unless of-course Asus are doing this out of the factory now. Go for OCZ Vista Gold, it's cheaper and the reviews say that Vista absolutely loves it, plus it always tends to work with the P5Q Motherboards.
You won't need a 600W PSU to run that, but it's worth keeping in if you plan to upgrade in the future.
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