Most seems the Quad core is better, according to e-Zone magazine, if we use it for Game playing, most of the application use one Core only. They recommend to buy E8500 is better as the frequency is much higher than Q6600. Moreover, it can save some electric power.
If we use it for HTPC, what is you choice...E8500 or Q6600.
Only for HTPC, choose E8500. higher frequency, low power cunsumption.
However, if you want to play nonlinear edit and code conversion.suggest you to choose Q6600