so basically if the motherboard is 2100 then i should search for that, i don't really have to worry about the 266mhz providing i consider the whether it's 2700 or 2100 if you know what i mean. i have a got a stick of 256 ddr in at the mo that's 266MHZ so the sticks i linked to would go well with the one in the machine at the moment and there is no point putting in a 512DDR module or does that matter?