Not sure, bliq has got a good point there, i was just looking at it on the net to see and it might not work actually. Your sytem is from 2006 and pci-e 2 started in 2007 so the card will fit but because your mobo is probably not 2.0 supporting it might or might not work . . . I don't know enough about that to be complete sure.
Otherwise this one maybe ; http://www.newegg.com/Product/Product.aspx?Item=N82E16814129091
it is pci-e 1.0