|"I need a new video doard"|
You already know the answer. We can't help you pick a card because you didn't bother to list your system specs. We have no idea which motherboard you have, the wattage of your power supply, how much you're willing to spend, or if you require a standard PCI, AGP, or PCI express card.
You also have too little RAM for Win7. It must be painfully slow.