Also if your stepping up to the Q6600 check out out Microcenter. They have them in store for 199. for the boxed unit. I posted this earlier and I have also seen the thread in Hot Buys. When you go in store you can also pick out the G0 step processor from the B3 if they have them.
Honestly I really don't think your going to run into to many b3's.... You might but I would not think so even if you ordered from the egg you should be getting a g0.