Dual core 3.0 Ghz, Triple core 2.3 Ghz or Quad core 1.8 Ghz?

I was looking to get a new processor (my old one failed). The options i have are: AMD Phenom II Dual-Core Mobile N660 (3.0 Ghz), AMD Phenom II Triple-Core N870 (2.3 Ghz) and a AMD Phenom II Quad-Core P960 (1.8 Ghz). It would be mainly used with Minecraft with shaders mod. Graphics will be AMD Radeon HD 4250 or 4200. 4-6 Gb RAM. Which processor would work best in terms of fps?

Triple core 2.3 Gs will be better. Minecraft doesn't require 4 cores so there's no point going for quadcore.