Don't think I'm disrespecting your rig b/c I think it sounds fantastic. However, your 3DMark06 scores sound low. I have a lesser setup (see below) but am outscoring you by 2000 points.
My score
The only thing I can think of as the cause is that 06 gives undue weight to SLI (I have 2 GTs, but every benchmark I have seen says they should be outperformed by 1 GTX). If you do go SLI, let us know your score. I am very curious to see how much it improves.
May the Flying Spaghetti Monster bless your system
WWFSMD?