I gree that going with PCI in this case is probably a good idea. Less to fight with for one thing and your system looks pretty good spec-wise, so you should be able to get a few years out of it yet. If I was in your shoes I'd go PCI myself.

The controller may have been installed while being connected to the front, I have seen some MIDI drivers that work only on the port they were installed to, so that could also be a possibility with the back ports. Maybe the fronts are somehow grouped..just a possibility.

I do not work here, but the benefits are still awesome
Make your sound your own!