I am tempted to say anything is better than that wintech-OEM'd Rosewill unit (since a $40 hipro 400w unit has better specs) but in this case the Xion's 600w rating is bloated with the +5v rating of 54A which is ludicrous for a modern PC.
Not to mention, they changed the label to "omit" certain specs that is needed to determine the limits of the unit - check out this Driverheaven.net review if you click on the link for the label pic you see the specs:
5v/3.3v/12v max combined=538w
So 360w/30A for +12v combined on a 600w? For $100? And you have to wait for a rebate?
My advice, get a decent 500w unit that can handle the specs like this Xclio goodpower 500w which holds the minimum SLI cert for PSUs so if it can handle 7800gt SLI @ 115w it should handle a 8800gts @ 105w no problem and it's a similar price to the xion w/o the rebate.