Both cards are the same except one is branded as XFX the other Powercolor. You are paying for the support by each company. XFX does have good support and is a lifetime warranty, (1 year if you don't register the product on their site, I believe). However, personally I never keep a video card beyond 2 years so that warranty isn't a concern for me. The Powercolor has a higher clock, which would be a benefit.
XFX has good support and a following in the gaming community so they will have alot of loyal "fans". But buying a powercolor will not give you an inferior product in any way.