If you know how to OC, I would say go with the i7 920. The higher end i7's (like the 950/960) are pretty much just OCd 920s.
My initial instinct says to get your money's worth out of that deal (because it's a very nice deal) and get a higher end CPU. But you could probably spend the rest of your budget elsewhere, such as graphics.
If you don't feel comfortable OCng, then you could look at the i7 950/960. With 1/2 of those, you'd be getting them for about the regular price of the i7 920.