You can do better then that.
Low end Thermaltake's aren't the best.
That unit is an old inefficient design and doesn't even have Active PFC.
Antec NEO ECO 620C 620W =supply your own power cord http://www.newegg.com/Product/Product.aspx?Item=N82E168...
OZC Stealth2 and ModX units are good for the price also.
^+1. The little voltage switch gives it away as an older, inefficient design; almost certainly overrated.
A quality modern PSU has full range active PFC (no little voltage switch) and [some level of] 80+ certification for efficiency.
Seasonic, Antec, Corsair, Enermax, and XFX are among the better brands. A 500W Antec Earthwatts would be a nice choice.
Unless you're planning to add a second GTX460, 500W is all you need. The EA-500D is the one I was thinking. The ones beanoslim's link shows would do too, with the OCZ below the others. It has had good reviews, but dissection may indicate some sub-par items like 85C capacitors so I don't know that it would last as long as the others (still, we're talking years here, not weeks or months).