PCI-E x16 v1.0 running at x4, whats the best video card I can run?

2.0 is 16gb/s. 1.0 is 8gb/s. this is a x4 slot so I'll assume 2gb/s, what stat on the card do I look at to determine the max throughput.|||You can run any video card you want.|||Any card you buy now will be backwards compatible with PCI-E 1.1

You would need a card going back to Nvidia's 7 series to use PCI-E 1.0