DON'T get the Pentium D. Get at least a E21xx and OC it. http://www.tomshardware.com/2007/09/12/pentium_dual_core/
Do Not Go For Similarly Priced Pentium 4 Or Pentium D CPUs
If you already checked Pentium Dual Core prices, you might have found several offers on Pentium 4 and Pentium D processors at similar price points. The clock speeds of up to 3.8 GHz are especially appealing, but these products are all based on the outdated NetBurst microarchitecture. It was designed to run high clock speeds, but it is clearly less powerful on a clock by clock basis when compared to Core 2. In other words: a Core 2 Duo CPU can process more instructions per clock than a Pentium D or Pentium 4. Please have a look at our Interactive CPU Charts, where you will find proof that the Pentium Dual Core E2160 at 1.8 GHz can sometimes even beat a Pentium D 960 at 3.6 GHz. In addition, the Pentium Dual Core requires less than half the energy, which results in a lower energy bill and fewer cooling requirements.