An eight or twelve on the response time is acceptable for gaming provided that it is the Black-to-White measurement and not the Gray-to-Gray. I've seen monitors with 8ms g-t-g, but they get 20ms on the b-t-w scale which is a little too high for gaming. The difference between 8 and 12 shouldn't be overly noticeable, but keep in mind that the lower it is the less likely you will be to see any ghosting.