Want to add 2 X 512MB's to a system that currently has 2 X 256MB's. Does it matter which slots the larger DIMMS are in? i.e. Do I just add the 512's to the 2 available slots or should I install the 512's in the slots the 256's are currently in and move the 256's to the other 2 slots? System is a Dell 8300 - P4 2.8GHz, DDR PC-3200 RAM.