What size of monitor do you plan on using? Also for gaming, you won't need anymore than 6gb in triple channel (if going for i7), or 4gb dual channel going for phenom II.
I'd definitely consider overclocking, especially if it's for gaming. You'll see the biggest benefit coming from an overclocked CPU.
If it is purely for gaming, then you could save your money and go with an AM3 setup, will be on par performance wise as the i7, but cost a bit less. Obviously the i7 is a better chip when other factors come into play, but for gaming both are roughly the same.