82580EB PCIe 1.0 compatability

[MJoyc1]

I need a quad port Ethernet controller and was looking at the 82580EB chip as a potential solution. My problem - I only have access to a x1 PCIe 1.0 bus. Does that bus have enough bandwidth to handle 4x gigabit ports? Is the 82580EB backwards compatible with PCIe 1.0? I know most chips are but I wanted to confirm.

Thanks in advance for any help.