ECC Memory has an extra chip on the memory that performs Error Checking and Correcting functions. It's really only recommended for machines being used as servers.

For home systems we recommend getting non-ECC memory unless you know you need the ECC function. This is because ECC and non-ECC memory can almost always be mixed in the same system with no problems. If you mix these types of memory, the system will run as if all the memory was non-ECC.

Non-ECC memory is also recommended because it runs a little faster than ECC memory since it doesn't need to do the extra error checking. ECC memory is only really beneficial if you're going to be processing massive amounts of data (like a server does) and all data needs to be 100% accurate. Non-ECC is all that's needed for 99% of the computers out there.