Did you connect the two cards via the bridge chip and plug power into the second card? I know its a dumb question, but some things do get overlooked when people are excited.
Try running GPU-Z and seeing what your cards are running at. Test them in 3dmark06 to guage what your performance is. Try only running 1 card and test again. Make sure all your drivers are up to date and installed properly (uninstalling old ones first).