Please remember that any mention of competitors, hinting at competitors or offering to provide details of competitors will result in an account suspension. The full rules can be found under the 'Terms and Rules' link in the bottom right corner of your screen. Just don't mention competitors in any way, shape or form and you'll be OK.
Brilliant exchange. Based on performance they could have sent a GTX 660, as a factory overclock on that would beat a 580.
IMHO if your GFX died within warranty and they dont have a similar card they should match the dead one based off the price and not performance. Like having your Bentley die but giving you a small Porsche that cost half but hey...its faster. It just doesnt add up.