G'day. It seems that your primary aim is gaming. If so, we have to ask, "will your graphics card be limitted by your cpu?" In your case I don't think so as the 6850 is a mid range card. Hence if I was you I would keep the current setup as you will not get massive gains in performance without also upgrading the graphics card.
Let's say that you want to upgrade, I would recommend an i5 2500 as it seems you have no intention of overclocking. Furthermore, if you are not overclocking, the stock cooler will be enough.
In gaming, an i7 will not help as the main difference is hyperthreading which is more suited to work programs.
In summary, I recommend keeping your system for another generation and then reassessing. Hope this helps