right now I have 2x 512MB DDR2 PC2 4200
in a Dell Dimension 9100
can I simply just add 2x 1GB PC2 5300 or PC2 6400 in the two empty slots and have 3GB of memory
or do all 4 slots have to have the same size and PC2 number.
I have only upgraded memory once so I don't know a lot.