According to your specs here
, it looks like you have a 180w PSU, which is amazingly weak. Now you MAY be able to run one of the midrange cards if it doesn't require a direct connection to the PSU, but even then that PSU needs a major upgrade. Just google the card you want and check the power requirements. It should tell you the recommended wattage for the PSU, which I garantee will be over 180w with even most midrange cards.