Hi, I have a MSI k9a2 platinum model number 7376. I have 4 1gig sticks of 800 mhz ddr2 ram installed. I wanted to know, can I replace just two of the 1gig 800 mhz sticks for two 1066 mhz 1gig sticks. That would make my motherboard having 2 800 mhz sticks and 2 1066 mhz sticks. I checked the motherboard and it supports 1066. Also, what is the differance, between 800 mhz and 1066? Is it really worth it or should I just buy another motherboard. Right now with all of the hardware in my computer I can run Skyrim on almost maxed settings on everything. I was just wondering. Also, I heard that windows 7 doesnt use more then 3 gig of ram anyways, is that true? I have windows 7 32 bit OS. Thank you very much!