I'm gonna order some RAM for the PC I'm building. I've got about 70 pounds to spend and just need some facts cleared up. Firstly, what is the latency? Secondly, what is the difference between unbuffered and registered RAM? Thirdly, what is the difference between ECC and NON-ECC RAM? P.S I would appreciate any suggestions on what RAM to purchase? (I'm looking for 1GB of 800Mhz).