You might want to bite the bullet and upgrade to a PCIE motherboard, keeping your current CPU if possible. You could then get a better video card for less money, like the 7600GT or maybe even something better. If you sell your old motherboard you will hardly be paying any extra.
Edit: Just checked, and there really aren't many socket 478 motherboards with PCIE. Only found one at NewEgg and was very expensive. Guess you'll need an AGP card.
Edit: Just checked, and there really aren't many socket 478 motherboards with PCIE. Only found one at NewEgg and was very expensive. Guess you'll need an AGP card.