A couple years back, I bought an open box ATI x800 card. Turns out someone tried to unlock some pixel pipelines on it and wound up frying it as it artifacted really badly.
That said, Newegg was very good about it and gave me a full refund with no hassle. The only catch was that they initially tried to charge me a 15% restocking fee but after a quick chat session to explain that it was broken upon my receipt, the customer service person gave me the difference.
So, I'd do it again.