Overclock your q6600 and get more ram.
Heat dissipation would be a problem. While the Corsair H60 does perform well (AS5 TIM) it is still limited by the ambient temp in my home (23*C) Right now I idle around 31*C and, under load, 62*C. Considering the age of the CPU I'm not that interested in burning it out and having to replace it. Not yet, anyway.
Currently, my computer supports Skyrim flawlessly on with graphics auto set to high. While I'm impressed that my current hardware can keep up, I'm still concerned about the gap between Core i* series CPUs and Core2 series CPUs. For what I do, would an upgrade really be worth it at this time?