Gigabit ethernet card for 2006 Mac Pro?

Hello Mac Pro Geniuses,

I have what I think is an original Mac Pro - it's a 2 x 3 GHz Dual-Core Intel Xeon and was wondering if anyone knew if the ethernet cards that came with it were 10/100 or gigabit? If they're not 1000baseT, does anyone know if there is a card available for purchase that is compatible with this computer???

Thanks!!!