Can't use two Celly's in the VP6, though.
I use two P3 1GHz @ 1.13 and runs great, although I killed one of those chips and am waiting for Intel to ship me another.
You will get one of the biggest overclocks out of the 700s but it's more difficult to get two chips to overclock the exact same. You will need to find two chips with nearly the same FP0/Batch number, identical stepping and identical stepping mask in order to get nearly identically performing chips. The 700 is no longer in production as well so I'm not sure how well you can find two, like chips.