Hey All ... I have a early 2008 Mac Pro which has 6GB of ram and it's constantly max'd ... I'm looking doing a serious RAM upgrade, but, not sure which ram I can get away with on it ... Looking locally, the ram that fits the spec for 8GB is like $400... (DDR2 FBDIMM 800) ... Anything else I can use? DDR3 SDRAM? Thoughts?