Well, my dad is pretty experienced in building computers, but he's having trouble helping me pick which type of RAM to purchase. We're building my own computer, and we've got everything but the RAM ordered. We know that the motherboard requires DDR3 memory, and not DDR2, but we don't know how many MHz the RAM should be. For those who would like to know the type of CPU, it is a Phenom II x4 945 (4 x 3.0GHz - 8MB Cashe - 4000 FSB), along with a Gigabyte M68MT-D3 motherboard. I'm looking at RAM, but it comes in MHz amounts of 1066, 1333, 1600, 1800, and 2000. If it matters, I intend on getting two sticks for 2GB each, totalling 4GB. Any help would be appreciated! Thanks in advance.