www.abithelp.com

Only get DDR3 if you have to. I'd have stuck with DDR2 if it was possible because it's half the price. Core i7 only has a DDR3 memory controller though, and requires low-voltage RAM (up to 1.65V), whereas DDR2 is usually much higher with a JEDEC standard of 1.8V (many overclockers go to 2.1V or more which would make the IMC very crispy indeed).