the q9550 is a great chip no doubt about it, but considering a q6600 can be free from a scrap heap if you look around a bit, for price to performance it is the best around. although, you have me tempted, I might soup up my optiplex with one of those chips...
the funny thing is I have much better computers but I really like that old optiplex...
also like iballew said, the 730 is better than the 240, and franly if youg et a core two quad, I would say the lowest GPU to get would be a R7 250, as the CPU can easily keep up, and a 730 or a 240 is really too weak for decent gaming.