House of Reps: Dems pick up 25 seats (15 needed for majority). Final result: 226-205.
Senate: Dems pick up 5 seats (6 needed for majority). Final result: 50-50 (with Lieberman and Sanders counted for the Dems). Republicans would retain control with the Cheney tie-breaker, but committee chairmanships would probably have to be split.
I think we get that result by having the Dems pick up Pennsylvania, Ohio, Rhode Island, Montana, and Missouri. I think Allen pulls it out in Virginia (though I hope not) and Corker beats Ford in Tennessee.
By the way, I'm hoping that my picks are way too pessimistic, and that the Dems actually pick up 35-40 seats in the House and 6-7 Senate seats (maybe even Arizona or Nevada will come into play?).
But I'm not getting my hopes up. GOP GOTV is impressive, and I think there are a fair amount of people that might tell pollsters they hate Bush and the Republicans, but secretly still vote for them when all alone in the booth. (The contrary is I think there's a chance polls are under-estimating Democratic turnout)