I am a fan of XFX products, particulary their video cards. I had a problem with a year old 7800GT card this past year and they replaced it no questions asked. Their warranty is amazing although the support is mostly web based, the corespondance from them was legible and not condescending. It was also resolved pretty quickly. Just make sure you fill out your warranty card information or submit it online.
I'm in the market for a replacement and will consider this as an optoin. Don't want to foot the bill for the 640mb version.