Can't help you on that, if it is not in the specs, and it could take hours to figure it out.
That is usually the problem, as it was new, they didn't say 1.0.
If it is 1.1, it is more likely to be in the specs.
1.0a came out in 2003
1.1 2005
2.0 Jan 2007
What was the date your board came out.
Acording to this 2.0 video cards should work, but no guarantees.
From Wikipedia
"PCI Express 2.1
PCI Express 2.1 supports a large proportion of the management, support, and troubleshooting systems planned for full implementation in PCI Express 3.0. However, the speed is the same as PCI Express 2.0. Unfortunately, the increase in power from the slot breaks backward compatibility between PCI Express 2.1 cards and some older motherboards with 1.0/1.0a, but most motherboards with PCI Express 1.1 connectors are provided with a BIOS update by their manufacturers through utilities to support backward compatibility of cards with PCIe 2.1."
Unless you are sure the mother board is 1.1, and you can get a BIOS update, I wouldn't take the chance.
If you do try and it doesn't work, you have the first part og your new build.
http://en.wikipedia.org/wiki/PCI_Express