I just purchased an I7 975 processor. I'm considering the ASUS Rampage Extreme or the EVGA Classified X58 motherboards. I like that the Rampage already has X-Fi, but I'm going to be using 1600 memory, which isn't natively supported. I'm not sure if I'll ever over clock but I'd like to have a board that supports an X-Fi card, 1600 memory, SLI or Cross Fire and possibly Phys-X or a Network Card.
buying an i7 975 and not overclocking is just a shame, but look into the dfi lanparty x58 any old low voltage ddr3 will work on most x58 boards with minimal tweaking so take whatever you like