Definitely go for the I7, you cannot compare clock speeds over different architecture. Higher clock speed is not allways better, it is like comparing a 3GHz pentium D to a 2.4GHz core 2 duo, obviously the core 2 will outperform the other. Hope this helped
I think Q9650 is stronger non oc in games by a bit small bit i believe but over all the 920 is a better cpu for things like transcoding and synthetics etc out side of gaming.
i7 is a better solution, simply for the sake of upgradability. For games though, the difference between the two are minimal, at best. If money is not an issue, go with the i7.