Taken from THG:
"The Pentium Dual Core, which we found to be an excellence choice for overclockers on a low budget, is based on the popular Core 2 architecture. In fact, the processor cores are the same, but the CPU comes with only 1 MB L2 cache instead of 2 MB or even 4 MB. In addition, some features, such as Intel's Virtualization Technology (VT) are disabled. The result is a castrated Core 2 Duo processor, using the small cache size and limited to 1.6 to 2.0 GHz clock speed at FSB800 system speed."
Please see: http://www.tomshardware.com/2007/09/12/pentium_dual_core/ for more information and a good overclocking article.