I have the Asus striker 2 formula and think its a great mobo alot of people like the Asus p5q and the gigabyte p45 boards are meant to be very good.
Q9300 when overclocked will be excellent for gaming and also very good for work. If your other build is going to be your work then I would get the Q6600 it should get upto 3.2ghz on air so will still be more then adequate for "work".
DDR2 just get 800mhz its a good all rounder for price/ overclockability the g-skill pi black sticks are meant to be good.