There is a review of boards on Tom's Hardware site showing the differences between many different makes. They are all pretty well the same speed wise. What makes the difference is features and for that reason, I like the ASUS line. The P8P67 deluxe comes with a few extras, like a USB v3.0 box for inserting in your case. It also has two network inputs vs one and a few other minor things. I didn't need this and saved $70 buying the Pro version.
The card should not be any problem. I run a GTX 260 and will soon upgrade to a GTX 570. The Pro can accommodate three cards but is designed for two in SLI mode...the connection strap is included with the board. The board is certified for Crossfire as well although would never recommend anything with AMD's name on it. [That statement is sure to wake up the sleeping regular posters!]
if you want PCIe v3.0 with 16x/16x/16x, you'll have to wait for the x68 chip set coming in the third quarter of 2011 along with the new 2011 socket. In reality though, the Sandy Bridge package is a lot of equipment for a low dollar and sure to please most gamers and general computer users...like me.
I picked the pro version only to have the option for sli in the future, but I seriously doubt that I will ever use it.
I installed a single GTX580. If, or when I need more, I expect to replace the GTX580 with the next best thing in single card format.
The board has usb3.0 and 6gb sata. Asus also has a web like bios interface, and several easy OC capabilities, which I have yet to try.
The nice thing about a micro-ATX is that you can put it into some interesting small cases. I used a lian-li V351.
I'm glad you guys pointed out the PRO series, that's perfect! Reviews look great, it's got the 6gb/s sata and CF capability if wanted in the future. And the price is better! Now that I think about it I prolly wouldn't have utilized the functionality of the deluxe. Thanks guys!