Well, it is always best to delay an upgrade for as long as possible. Although and i5/Z77 would be much better, it may not increase fps as much as you expect since you will still be running a GTX660. Are you noticing unacceptable performance right now or is this more precautionary. If the latter, wait a few months, save some money and then reassess. It is better to spend more less often then vice versa. Most MMOs are not that resource demanding.