Actually for most graphics cards you will NOT be able to fit pci-e cards into a normal pci slot because pci-e cards have more pins than the pci slot can fit.
Will A Pci Express Card Fit Into A Pci Slot?
PCI express is a great card. And you'd be able to use the pci slots to fix there your new PCI express card. Here is some more information about the card. Click here to see more about this card.