+1 for P45. Especially if you dont need SLI. The P45 board is a bit cheaper and should be better quality (8-phase vs 4-phase power regulation). Also the P45 should have a combination of more and/or better NB/SB features.
If you are going to (eventually) run in SLI, then you have no choice but to use an nVidia Mobo. If you aren't wedded to SLI (2 nVidia GPU's), then dollar for dollar an Intel P45 is clearly a better motherboard. Period, end of discussion.
According to Tom's 2 x 4850's is the best bang for the buck if you want 2 video cards. So, the P45 chip set MB. Unless you wait for the x58 MB's with (some) both Crossfire and SLI capable and a Nehalem to go.