i think silverstone op1000w is good only for cpu overclking , especially quadcore.
'coz it have rock stable 12v volt. under load, and 12v=12.45v.
there are lots of solid caps arround cpu, so ripple noise is not a big problem for cpu.
but for vga...maybe it's not good
i'd buy 2*vga power for vga card + sst op1000w for a xtreme overclking.


about Crossfire, yes, more efficiency than sli.
both 01/03/05/06 score(or part of) improve a lot compared with 8800gtx-SLI.