k dont buy 850WATT PSU, are u craZY! get OCZ PowerStream 600Watt, AT MOST, or just stick to regular antec truepowerII 550watt, it handles any current SLI.
Switch ram to G.SKill Xtreme 2x1GB PC 4000
switch HD to 1 36GB and 1 250GB
switch GPU for a 7900GT
switch CPU for Opteron 165
and that comes to a total of, WHOA 1337, lol, around 1400 depending on prices in ur area, and its still kickass if u overclock the Opteron. wait make that around 1500 i forgot to include PSU.