ECC-capable RAM doesn't mean anything unless you have an ECC-capable motherboard and you have ECC turned on in the BIOS. You can mix ECC and non-ECC RAM easily and with no problems, as long as you don't try and enable ECC in the BIOS with non-ECC RAM in the system. ECC RAM is typically used in mission-critical servers and not much else, and it can slow performance a bit. Hate to pimp my own sale, but incidentally I have a 512mb stick of non-ECC Kingston PC3200 for sale right now, CL3 and everything. It's listed in the "BUY/SELL/TRADE" section, but you need 10 more posts before you can enter that forum.