What are the requirments for the mac pro? I just bought mine, and its shipping with two 512 sticks. I am ordering two 2 gig sticks from crucial. With the ram pairing, and the 2 risers, how is the proper way and order to install this ram? Do both risers need to have ram in them? 2 sticks in top, 2 sticks in bottom? And, if I decide to add ram past my 5gigs (as above), does the ram need to be added 2 sticks at a time? and, do the risers need to be balanced with eachother? Thanks in advance!