Funnily enough, the cpu in the system i sold, was an E6300, but it was one of the old Allendale ones. Awesome cpu, ran every game I threw at it.
I was leaning more towards the E7500 because of the extra cache, which is essencially what I would prefer to have for gaming and whatnot. I will however, take your advice and go for the EP31 instead since you say its great for overclocking.
As for the graphics card. Well, I havnt had a good history with ATI cards, and while the 4870 may be a little better, I might very well stick with the GTS250 just to put my mind at ease.