Mogens,
When you say "refrigerator-sized monsters", did you have this kind of machine in mind?
Also, I'd suggest you replace those 20 Sun servers with a couple of Opteron-loaded standard boxes. Just for your main production environment, mind you. Might be easier to handle a couple of standard PC boxes than all those refrigerator-size monsters out in the big, cold room.
http://www.sun.com/servers/highend/sunfire_e25k/index.jsp
Sun has opteron based servers (the Galaxy line of servers):
http://www.sun.com/servers/entry/x4200/ http://www.sun.com/servers/entry/x4100/ http://www.sun.com/servers/entry/x2100/
http://www.sun.com/servers/coolthreads/t2000/ http://www.sun.com/servers/coolthreads/t1000/
James http://jforonda.blogspot.com/ -- //www.freelists.org/webpage/oracle-l