Unfortunately you wasted your money on the DDR3. The Q6600 is not that sensitive to increased RAM speed. You may get a little more due to the increased FSB at the lower multi but I suspect it will only be noticeable in benches. Since you have it you might as well play. The increased FSB/RAM speed will put more stress on the mobo, so run different settings to determine whether you "feel" like the additional stress is worth it.
Since you are new to OCing, I suggest you do the intermediate OCs that I suggested above and test load temps before moving higher.
small FFTs to load the CPU.
Use Real Temp 2.75 Beta
to test the core temps.
I strongly suggest you read these links as well.Core 2 Quad and Duo Temperature GuideHOWTO: Overclock C2Q (Quads) and C2D (Duals) - Guide v1.6.1
Be careful you can easily significantly shorten the life of the Q6600 at 3.6G.