I would go with the P8P67 Pro, for 3 reasons.
1.) The extra PCIe x16 slot.
2.) The Sabertooth's Thermal Armor seems kind of cool, but it worries me. Seems like after a while dust might get trapped in there.
3.) The P8P67 is $50 cheaper. Probably the biggest reason.
Also the P8P67 has bluetooth if that matters to you at all.
For the power supply I recommend at least considering the Corsair Enthusiast Series CMPSU-650TX 650W. It got excellent reviews and is in the same price range. Plus there is currently a $10 rebate. (Price after rebate is $84.99)http://www.newegg.com/Product/Product.aspx?Item=N82E16817139005
Whatever you end up deciding, good luck on your first build!