blacksheep123 :
a 5ms IPS panel will do the job
In adventure/RTS/RPG/etc games, sure. In FPS and other fast paced games, the difference between a 5ms response and a 1ms response is significant even to a casual gamer. You movements feel more accurate.
Also, an IPS panel will generally only have a 5ms response time if the circuit is very short - i.e. the only connector is a single DVI port. anything more and the refresh time goes up.
Having said that, an IPS panel will be sharper than a TN and I personally use an IPS panel because at the time I bought it, it was the only way to get 2560x1440 resolution at 120hz.