I have a 2009 MBP (in sig) which currently has 4GB of 1066mhz ram. I want to upgrade to 8gb. A 8gb 1066mhz kit costs the same as a 8gb 1333mhz kit. If I get the 1333 kit, will it just run at 1066mhz in my machine, and what happens to the latency? I read somewhere it might run at the better CL7 when at 1066mhz instead of CL9 at 1333MHZ. There is a reason for doing it this way, before you all suggest getting the 1066Mhz ram. My wife has the 2011 mbp with a 4gb 1333mhz kit. When I upgrade my mbp (probably after the next 2 revisions, by then it will likely come with 8gb preinstalled) I want to be able to give her the 8gb RAM from my machine. If I have the 1333 kit already she wont lose any speed.