Always better to game over Ethernet rather than WiFi. Of course, WiFi is just so darn convenient
. Anyway, the principle of the cooler on that 4870 is the same as on your 9600 there, except bigger. So long as you have decent airflow you should be O.k with your PCI card. You could also replace it with a USB wi-fi adapter, like $15 from CompUSA or newegg, rather than making holes in your wall.