I just purchased new memory modules and have a couple of questions. I removed the original memory 2 RIMM RamBUS 128 MB/16@300mt/s 600MHz ECC RDRAM with 2 RIMM RAMBUS 256MB/16@400mt/s 800MHz non ECC RDRAM. Can I install all four modules on a Intel 850GB motherboard or are they incompatible. When I replaced the memory I had to reactivate XP. Will I have to reactivate if I install the 128 sticks and if so will this be a problem. Thanks for any info you can give me. My next project is to install a new video card.