Intel Dual Core vs Quad Core Revisited

It's very interesting to compare quad-core and dual-core processors, as the cheapest Intel Core 2 Quad (Q6600) already costs about $200. This price border separates more expensive CPUs from popular products in the market. So, common users may be tempted to buy a real quad-core processor, even if it does not operate at a high clock rate. We only have to find out whether it's an objectively expedient decision.