okay if you're partial to amd, you can get the 4200 and do a small overclock on it. it will offer you comprable performance of the e6300 and it's a little cheaper.once you get into overclocking, though, you will only be able to achieve (and it takes work) close to 2.9 with the 4200, an increase of (maximum) 7-800 mhz.
with the 6300, you can probably get past 3.0ghz, an increase of 1100mhz. so, it's up to you. product loyalty is great. that's why i bought my amd, and i have no regrets AT ALL. but, if you are looking for the top performer right now, c2d is it.