Not familiar with that XFX model and din't find many reviews.....if it was the "Black Edition" I woulda said grab it as the Blacks are comparable to Corsair's top of the line HX series. The Corsair TX is comparable to the Antec EA series below and is a very good PSU.
For comparison purposes , the list below contains performance ratings (10 scale) at jonnyguru.com / prices as per newegg on 02/26/2010 and ones w/ double asteris (**) made it onto silentpcreview.com's Editor's Choice List:
Note: Just because you see a brand name on this list, never make the assumption that their other lines are of matching quality. Silverstone for example has other models w/ 6.0 and 7.0 ratings.
"XFX 650 W XXX Edition is a very good power supply, being capable of delivering its labeled wattage at high temperatures, keeping high efficiency if you pull up to 80% of its labeled capacity (i.e. up to 520 W), a three percent voltage regulation (as opposed of 5% as defined on the ATX specification – translation: voltages closer to their nominal values than required), low noise and ripple levels, modular cabling system and a single-rail design.
Another nice feature is the presence of four connectors for video cards, allowing you to install two video cards that require two power connectors each. Some 650 W power supplies from other manufacturers have only two of them, and some users only discover this when it is too late (i.e. after buying a second video card and trying to install it).
It presents a good value for the average Joe............ And the five-year warranty certainly counts positive points towards this unit.
When we opened this power supply and saw that the printed circuit board was from PC Power & Cooling Silencer EPS12V series, we thought that this unit could be a relabeled Silencer 610 with a modular cabling system added, but our suspicion didn’t hold true: this 650 W unit uses rectifiers with greater current limits on the secondary, plus more powerful transistors on the active PFC circuit."