Well, the Q6600 is going to hold you back a LOT; while still capable, its old, and will suffer latency problems due to relying on the FSB. The 650ti, likewise, is OK, but not really meant for maxing out games, and will suffer FPS drops on hard to render scenes.
Frankly, your rig is doing better then I would expect based on the HW.
Thanks for the help! I'm thinking of upgrading my CPU to i5 3570 3,4 Ghz.. Do you think I will get way more fps than I already have (10 plus or more) in general or not?
I forgot to mention above that my fps drop from 45 to 15 after 5 mins of playing..