I believe the XFX warranty is 5 years if you register online. newegg lists 3 years.
The Antec High Current Gamer 520W is currently about $50 shipped (3 year warranty).
Internally it's pretty much the same as the XFX--same Seasonic platform, all Japanese capacitors inside and decent build quality.
520W is enough to power a i7-2600k and GTX 580 unless you go wild with volt mods and overclocking on the GTX 580.
It sounds like maybe the XFX still might be slightly better? It's hard to say but they certainly seem very close...