Easy stuff. You can either set your BIOS to run your computer the way you want first, or install the OS first by starting it with the windows CD in the drive.
In the BIOS, set the RAM to the settings which they are programed to run at(if you're not overclocking) by setting the RAM speed to manual, and selecting the speed yourself. You may need to set the voltage to it's specified power as well. (not above 1.65v)