Chris, two things to try - some other USB item on the USB cards, to make sure that they work, and if you can rule them out, try the mouse on another computer to rule it out. We know the mouse is getting power - since it lights up - so something is happening at least.
If both PCI cards and the mouse work in other circumstances, then there is something particular to your setup & this combination that is causing the problem. Maybe a bit more info will help - which Mac are you using?