from another forums:
ECC RAM is error checking RAM. It is not necessarily for servers alone. Many high performance computers/motherboards will accept either ECC or Non-ECC RAM. Check the system board specs to determine what type it will accept. You will pay more for ECC than you will for non-ECC RAM. Perhaps more importantly when using the new 64bit processors on a system board, you need to check the RAM for it's CAS Latency rating. It is possible to buy high quality RAM, ECC or not, that will not allow a computer to boot because the CAS Latency rating is not compatible with the PROCESSOR. Be careful and spend extra time to research for the appropriate RAM. Also, forget about trying to save money by buying it online from the most inexpensive place possible. Do yourself a favor and buy from a reputable dealer who allows you to return and exchange if you have difficulty with your purchase. I recently built a new 64bit system and purchased all of my components from NewEgg online. I've spent the last 17 years working on a technical basis in the computer industry and even I needed to take advantage of the return/exchange availability.