Is it worth it? My friend is getting rid of his GTX 670 superclocked - http://www.amazon.com/EVGA-SuperClocked-Dual-Link-Graph... and said he'd sell it used for 250 or best offer. I currently have a Radeon 5850, I'm a hardcore gamer but have a limited budget so I've been pushing off a card upgrade for a while. Is it worth the upgrade? And is 250 a reasonable price?