My Vista (64 bit Ultimate) hates my ram. Whenever I try to add more than 2 gb (I have 4 2gb sticks), Vista gets veary unstable as in locks up or randomly reboots. I've tested each ram module in my old desktop, they all check out. I also installed the KB 929777 update which was supposed fix some RAM issues, but it didn't help. My vista fully up to date as is the drivers to the rest of my components.