well the Q8200 is a good proccy i am currently using it. got it overclocked to 3ghz no sweat on value ram. im sure i can push it further soon as i get a good cooler and better ram .
the advantage of Q6600 is that it has more amount of cache and ppl have easily hit about 3.6ghz on it.
but Q8200 is 45nm compared to Q6600 which is 65nm. so more cooler and lesser power conspumtion.
as for the mobo, MSI p45 platinum is a good board. im using it myself