I recommend the i5-3570K CPU. Not only is that the recommended gaming CPU for new builds but it also has and adequate GPU for Minecraft.
If you use MAX quality at 1920x1080 you only get 25FPS, however just a small adjustment and you get 30FPS plus (maybe just go to 1600x900) which is fine for this game.
I don't own Minecraft, but hopefully it will VSYNC to 30FPS to avoid screen tearing.
*Torchlight 2 is apparently quite playable on the i5-3570K's HD4000 graphics: http://www.youtube.com/watch?v=HQ98GkyUmcE