I am looking at a Rev A Mac Pro with the 2x Dual Core 2.66 Ghz 5150 chips, 1GB 667 Mhz RAM, 250MB HD. (the standard model from August of 2006). I am told his comes in the box, but It does not have the keyboard or mouse. What should I reasonably pay for this machine? Also, I'm planning on upgrading the RAM. Is there any problem adding 2 2GB chips to the existing 1GB (5GB total) or should I just pull the 1GB chip? Thanks for helping a Mac noob.