I'm upgrading my computers memory, right now I have 1 512Mb chip set already in the computer. Now I can afford to buy from Crucial ethier 2 1Gig chip sets for a tottal of 2.5Gig's(2 1Gig's + 1 512Mb), or I could get 3 512Mb chip sets for a tottal of 2Gig's(4 512Mb's). Which one would be the better one to go with because I know you should usally keep all the chip sets the same memory.