Yea just found it at Wikipedia
"PCIe 2.0 is completely backwards compatible with PCIe v1.x. Graphic cards and motherboards designed for v2.0 will be able to work with v1.1 and v1.0, and vice versa. In some rare cases it is possible that a PCI-E 2.0 card will not work correctly on a PCI-E 1.0a slot. This is only limited to certain video cards."
I hope I'm not in one of the "rare cases" gona go buy me a 9600GT now!