XFX offers a lifetime warranty for both Nvidia and ATI cards. BFG also offers a lifetime warranty. EVGA used to, but I haven't seen it on their cards' specs of late.
xfx also allow you to remove the stock heatsink and still not void the warranty, you just have to put the stock one back on if you are going to send it in/back.
Very nice guide. This is quite helpful even to a pro, as its impossible to remember ALL those cards, especially comparing cards from different generations. Great job guys. Keep up the good work, and add in the 5770 and 5750
XFX offers a lifetime warranty for both Nvidia and ATI cards. BFG also offers a lifetime warranty. EVGA used to, but I haven't seen it on their cards' specs of late.