I'd buy one which has a high-rated 12V line.
Actually I'm a bit surprised that some psu manufacturers seem to have missed that nowadays you need more power on the 12V line than on 5V/3.3V. Nodody needs 45A at 5V, since todays motherboards use mainly the 12V line for cpus, and the high-end graphic cards also mostly draw from the 12V line (that's at least what everyone assumes, I don't know how much the cards draw from each rail, the card makers don't tell, and nobody has bothered to measure it!).
Yet there are lots of psus out there which have a 480W rating, but only 18A on 12V which might get you already into trouble with that prescott 3.4E + NV40 Ultra. Some manufacturers have realized that though, the enermax 350W for instance is rated at 26A@12V.