Logic behind the Presler 965 versus the Conroe x6800

On TomsHardware CPU Charts page (considering just about every test performed by the author – including real world tests such as running movies, decoding, multitasking with WinRAR… etc) the Intel Extreme x6800 outperforms the 965 Presler. BUT – the Presler is a single core – 3.73GHz processor… whereas the Core 2 Extreme x6800 is a duel core running at 2.93GHz. Can someone explain the logic behind these test results, as in why two cores running at 2.93 is able to out perform one core running at 3.73. A person may quickly assume that it may be as simple as a multiplication of the speed times the number of cores but this is not necessarily true due to bottlenecks. I appreciate any explanations someone may be able to give me, so I can make my purchase.