Welcome to the addiction mhorgel. I'm using Ubuntu Server 10.10 64-bit. It might be easier to get Ubuntu Desktop up and running. I have a little Linux experience over the years, but not much really. I was able to get the Ubuntu server up and running with just Googling around on how to do stuff. I put up some instructions there on getting it working with the 64-bit OS. Which from what I hear crunches better than a 32-bit OS...As far as CPUs, they need to be the same model. Like all Opteron 8347s. Other correct me if I'm wrong. eBay is probably the best place to look. Set yourself up a search alert.