Nice spec. With that budget deffo i7.
The X58 boards are the top of the range boards for i7 afaik. P55 should be out Q2 or Q3 09. Same as P45 and X48. Intel decided to bring out the top X58 board to cash in on people who have to have the latest spec and are offered no alternative.
X58 will be x16 on all PCI Express slots. As is X48.
"Core i7 1366 Support, 6400MHz FSB, Triple Channel DDR3 Support, 6x SATA, RAID, 8x USB2.0, FireWire, 7.1 HD Audio, Crossfire/SLI Support, Silent Heatpipe, Dual Gigabit LAN."
Supports both Crossfire and SLI.