AS5 is one of the best thermal pastes out there, for the money. MX-1 though, being around the same price, is a little better. It's just a little harder to come by, compared to AS5...but it is available at newegg.
The P35-DS3R is certainly, the motherboard to go for...being a monster overclocker and futureproof as well. Another one that has a bit more features, non-SLI, is the MSI P35 Platinum. That has been getting monster overclocks too. Though a bit more expensive, because of the added features.