I think i am right in saying that if the new
ram has the same speed (mhz) and its the same compatible model (ddr,ddr2,ddr3) then it should be fine, so unless you are considering getting rid of the old
ram (considering it is ddr2667) then there is no point in getting hugely expensive top of the range
ram, because if you have really old rubbish
ram then adding some good new
ram in will do nothing.