I want to install additional ram in my system. I currently have 256mb PC800 RDRAM (2X128mb). System is a Dell dimension P-4 1.7ghz. i850 board. I wish to install another 256mb. My question is what is the difference between ecc and non-ecc ram, how do I know which type I have,and can you install a pair of non-ecc rdram with a pair of ecc rdram? Any help would be appreciated.