I believe MOST P4 system boards are Rambus/DDR RAM only, although you can now use PC 133 memory with some them, depending on what chip set you are using on your motherboard.
I haven't put together a computer from scratch in 1.5 yrs, and unfortunately working in a place where buying from Dell is standard, I don't think I'll be building one there any time soon. My PC is a 750 at home, so I don't need to upgrd. yet, meaning I havn't had to keep up with the changing technology too much. I think most AMD systems will use the PC 133, although I know even less about AMD systems since I've NEVER put one of them together. So if anyone else can help with the AMD side, feel free. I believe the PC 150 memory is for the newer Athlon's.
[ July 08, 2002: Message edited by: slerch666 ]</p>