Hi, I'm looking at buying a new SATA hard drive and would like to clarify a few things. First, I know there are SATA-150 and -300 versions. Is a motherboard restricted to just one or the other? If a motherboard can only use one, say 150, would a 300 work and just not run at its max? Also, I think it's the buffer (usually 8MB or 16MB) - which is better and what do they do? I very much appreciate any answers, thanks in advance!