yeah i don't see why not.
i'm pretty sure it's 1.0, you could always download gpu-z and it'll tell you what interface your card is running at, i.e. pci-e x16 @ 16 or pci-e 2.0 x16 at x16 or whatever.
i used a 4850 on a pci-e 1.0 mobo and got ~30fps in crysis running is on very high. i was really impressed.
you might want to buy it from somewhere that you can return it (like fry's, although they don't have the best prices) just in case.