It's a very nice rig

. I remember reading something about overclocking the FSB of Xeons, but I would not try to push them that far. Something is sure, I won't overclock our Dual 2,8 GHz Xeon server at work

It runs 24h/365d not a good idea.
Now you have to take care of your video card, it's not up to the same level as the rest! Maybe a dual GeForce 6800 Ultra could keep up

.