If you want two nVidia video cards then I'd say eVGA 680 A1. For two ATI video cards, P5W-DH is still a good option, or GA-P35-DQ6, or wait a bit for an X38-based motherboard.
If you only need one video card, you probably want something based on the P35 chipset. Some of the most popular models are Asus P5K, Gigabyte GA-P35-DS3R or GA-P35-DS3L, aBit IP35Pro.
The differences in performance between motherboards are negligible. I've seen lots of reviews where you get 103 fps instead of 100 fps if you change motherboards, etc - you wouldn't notice the difference.
Some boards overclock better than others. Those I mentioned are good at it, by the way.
Instead of looking at performance you should look at features. For example decide if you need two video cards (and, if yes, what kind - ATI or nVidia) or FireWire, or wireless, etc., then pick a motherboard that has what you need.
The p5w-dh is a good option but is a little slower than the evga 680i mostly cause it has more stuff that you may or may not use in the whole package.
my only complaint about the evga board is that you have to download the full manual to make sure you don't do things like plug in the usb front panel connector to the 1394a pins on the MB or mess up the front panel headers since the board isn't exactly well labeled.
After you are setup, the p5w-DH has more options for "stuff" in windows like built in wi-fi and that slows it down a little if you use it. But other than that both are good.