Always good to have a 2nd set of eyeballs looking things over.
CPU/CPU cooler/MB/RAM: all very good choices. Can you find the P7P55D-E (not LX) version of that board? 2nd x16 PCI-e option there (x16/x4).
I couldn't figure out the exact model of that Geil Black Dragon RAM but I did find a review of a 8GB Cas7 kit and a 4GB kit that give me confidence your pick is a good one.