RAM timings only determines the performance of the RAM.
I'm not sure how video editing works, but it seems logical to me that the video data or a part of it is stored in the RAM, because this is much faster than reading from the hard disk. If you don't have enough RAM, the data will be stored in the virtual page which is on the hard disk, resulting in a significant performance loss.
I think having more slots of RAM also decreases your CPU's FSB speed though, resulting in a differential RAM:FSB frequency ratio, which wouldn't help, and can ultimately slow down your CPU..
If possible, you want the least slots of RAM at the best performance possible. My 2GB's running at 3-4-4-9 @ 1000mhz will out-do any set of 4GB any day... I'm sure. I dunno if this applies so much to graphics mind you .
I thought the stability of Windows with a C2D CPU is because it's slightly underclocked already.
I dunno, another clicker told me overclock leads to a less stable system. I've found no need to overclock my C2D. Not voiding my 3 year warranty
It does lead to an unstable system, IF your CPU gets too hot through the voltage you send into it to OC it etc. that's why I have watercooling and im running at 3.6ghz from 2.4ghz, and not at 4ghz... because at 4ghz my RAM is unstable, and so on
It's getting the right balance of a multitude of little things.