Well, for $150, the best you could get a Radeon HD 4850 for $130.
http://www.newegg.com/Product/Produc...82E16814102770
But for WoW and L4D, you really don't need a 4850. A Geforce 9600 would be perfectly fine.
http://www.newegg.com/Product/Produc...82E16814500077
