I have 2GB on my machine. 2 sticks 1GB each. So I want to put 2 more sticks. I went to www.crucial.com and it told me I should "get DDR 3200 or DDR 2700 and since these are backward compatible I can get them even if my motherboard manual says to use DDR 1600". To which I have to say..."Huh?" I don't have my motherboard manual. I just need to know that as long as I use the same speed on the two new sticks I'll be okay? Or I have to use the same speed as the ones I have now? How do I tell? Also it says I can use ECC or NonECC RAM, but no to mix. How do I know if I have ECC or NonECC RAM now? I was hoping there was some memory diagnostic tool that would answer this question for me. That or someone else here who has the same motherboard and can just tell me what to get without having to go over my existing sticks with a microscope. Thanks in advance for your patience and help.