Fyo, Re: I'm not sure what you mean by adding "dual channel DDR memory", but since Banias uses the same bus as the P4, using it with a P4 chipset would be "simple".
Perhaps I should have said, "Add socket 478 support," instead. Banias will not fit into motherboards currently designed for the Pentium 4, even though it uses the same bus protocol.
However, assuming you could get a Banias CPU into an i875 board, I think it might give Pentium 4 a run for its money in applications that are not Hyperthreaded optimized. In those apps, I am skeptical. Also, we have not seen Prescott, yet, so at best, Banias would be a good Northwood competitor.