For gpu cards, I personally prefer going through a company with a lifetime warranty. For ATI cards, this means XFX and Visiontec. I haven't seen any Visiontec 5 series cards yet, but I haven't been looking terribly hard.
I have bought 4 cards from XFX over a period of about 6 years and all were well packaged and non-DOA.
What you might want to take into consideration is the supplier your buying the card from; I only deal with newegg and tigerdirect as they both have good customer service reputations.