After you install new RAM in your comp can you leave the old RAM in also?

[Mutant Corn]

wow! really??!!? so my computer can go even faster?

RAM only speeds up your computer if you're using all of it. I doubt you'll see a performance difference between 4GB and 6GB. Still, it'll future-proof it a bit. More RAM can never hurt.

As far as the speed goes, there's two ways to list it:

DDR2 400 = PC2 3200

DDR2 533 = PC2 4200

DDR2 667 = PC2 5300/PC2 5400

DDR2 800 = PC2 6400

DDR2 1000 = PC2 8000

DDR2 1066 = PC2 8500