Duo Core 2 6300 or am2 socket dual core 4200+ neither overclocked.
Definitely the E6300. Even though the X2 4200+ is 2.2GHz, compared to about 1.8GHz for the E6300, a Core 2 Duo is the best line of dual core CPU's out there. Others will agree.
i concur. i have a E6600 core2duo of my own and the performance is fantastic and have recently had to purchase 70 computers for work and everywhere pointed to the E6300 core2duos being the best for the budget.
From what I have seen the E6300 is the faster.