I am also planning to build a gaming pc. after research, I found that the fx 6300 will be the best choice. the intel i5 will of course be better but the fx 6300 will be the best for the price. the fx 6300 will be good in overclocking.
Also, after watching a lot of videos comparing the gtx 660 and the hd 7850, I saw that the gtx 660 2gb (non-ti) does much better in some games like farcry 3. you wont get good fps with the gtx 660 or hd 7850 if you play on high on crysis 3, I prefer you play on medium. Bf3 will do good on ultra with both graphic cards but I still recommend the gtx 660. I hope I was helpful (:
If you want budget the fx 6300 will do good. Just overclock it and it will perform quite well. And well the i5 will be better it's not worth the price increase if you have to step down in GPU performance especially if you OC the 6300 it will close the gap a lot more between the two.
The FX 6300 is pretty much the perfect compromise at the moment. It has enough cores to make it useful for media duties, while having enough speed to run games at decent frame rates.
When overclocked it can match a stock 3570 in some titles and loose only slightly in others. If you plan to overclock get a decent third party cooler though.
Shop around a pit for your GPU there are some nice deals out at the moment with AMD releasing the 7870 with a cut down 7950 chip in it which performs really well. The powercolor Myst card is one such card.
Almost everyone seems to suggest that the i5 is better, however, I don't know if I want to pay another £100 for a small increase in graphical performance.
Like most things you get what you pay for. The I5 cost more but is an overall better CPU in single threaded programs like games. That is backed up by tons of benchmarks in the computer industry. If you can afford the I5 I would go with that and not think twice about it.