Take the card out and sell separately. Add in some fancy neon LED's to the case if not already there. Sell vidya card for $100 and rest of the computer on ebay for $500. Even though it'll have integrated graphics, noobs will see the LED's and go "OMG! POWERFUL ALIENWARE GAEMING PC!111" and buy it anyway.
Be sure to include phrases such as "Quad core" and "Powerful gaming pc" in the title for maximum effect.