Went to crucial first but they dont carry RDRAM. This is from price grabber-kingston was more expensive I think... I have 4 slots with 2 64's in 2 of them-at least thats what it says-I never actually looked in there. I have never put in memory-I have put in a zip drive and a sound card-that was easy..Im not sure if I have 800 or 600 how do I find out-shoud'nt this be easy too?