what is the performance difference between pci-e16 2.0 and pci-e16 1.1 ?

I have a mobo that supports pci-e 16 v 1.1 I know that v2.0 is backwards compatable, but I am wondering if I should shell out big bucks for a more advanced graphics card, if it won’t perform to its maximum potential. Is there a big performance difference between a 1.1 slot and a 2.0 [...] http://bit.ly/psPZG6