If you installed the drivers before putting the pci card in the PC, this can sometimes cause a problem.
Alternatively if it did boot with the card in prior to you installing the drivers. Download the latest drivers form Safe Com this may fix it.
Either way you need to remove the drivers that are on your PC now. This should help explain how.
If that fails, write back and I am sure someone will talk you through checking the PCI settings in your PC's BIOS.