New Ram (Help Convert a Heathen!)

Help convert the heathen! lol. I know nothing next to nothing about overclocking, but certain websites have piqued my interest in the past few weeks.

Right now, my system has 768 of ram, a DDR400 of 256 and a DDR333 of 512(long story as to why I have these two dimms. Look for it in the mobo folder). My new CPU and mobo have prompted me to replace the memory, and toss it into one of my "spare part rigs." I'm running a P4 3.0 on an intel p865BFG mobo.

The board has 4 dimm slots for dual channel DDR400. I'm having a very hard time finding any real information on dual channel memory. Reading between the lines, I'm under the impression that the system sees both dimms as one larger dimm, and accesses both at the same time, which speeds up memory bandwidth. If I'm off or completely wrong, please enlighten me!

I'm looking mainly for some information and advice about what ram would be a good choice for this system. Although money is a concern, I'm not opposed to spending a bit more for a product I'll see better results from. Overclocking the system will, more than likely, begin after the memory, and possibly mobo, is upgraded. An Enermax CS10801 case with 7 fans must be a sign from above that it was meant to be! Right? LOL.

Well, i dont know about the accuracy of your annology, but i do know that expecially in intel systems dual channel will give better performance because you are saturating the FSB. For a more technical explanation of dual channel:

DDR 400 will communicate with the CPU at 200 MHz twice every clock cycle (main system clock) meaning the main system clock will run at 200 MHz while the DDR sends data twice per tick thus having 400MHz.

When you make dual channel DDR, you basically have 2 individual channels (perhaps this is done with dual controllers, or a split minded type controller) But now, on the rise of each 200MHz clock cycle DIMM 1 will communicate at 200 MHz and DIMM 2 (assuming only 2 DIMMS exist) will communicate at 200MHz at the exact same time leading to 400 MHz total communication speed on JUST THE RISE of the clock. On the fall of the clock cycle, the same thing happens. This fully saturates the 800MHz FSB of the newer intel "c" cores. I dont know how to define the rise and the fall of the clock cycle but i know basic SDRAM only communicates once per clock and that DDR communicates Twice and rise and fall are the technical terms for those two communications.

How it works: http://computer.howstuffworks.com/ram.htm