Browse NewEgg and get a picture of the card. If the AGP connector looks like the card on the right and says it is 8x, it will work:



If it looks like the card on the left, it will take some digging to know if it will work because of the voltage issue Tony talked about above. Some cards are "Universal" and can work at eithe rvoltage, while others demand 0.8v only. This site goes into detail on it.