That PSU is out of stock on newegg. Plus the XFX has more amps on the 12V rail. It is not always about wattage.
The CX600? Oo
It has a bigger 12V rail than the XFX (46A vs 44A) and it is in stock on newegg. Dunno how tricky rebates are (not in the states, and we don't really get them across here) but if you can really pick up a decent 600W PSU for $40 then its a great deal.
Regardless, either is a good choice.