Hell i even but that the 44418 ram could run at 44412 without a problem. I know i got my 4x1gb of 800mhz ram to run at 900mhz 4-3-3-12
I run 4gb, and the only OS Im glad I have it for is Vista.
I could never see a difference in XP (outside of Crysis), and I DEFINITELY havent seen a difference in Kubuntu.