Rated from 650W to 750W, Corsair's new “TX” series are designed to give 80% efficiency ratings even up to 100% load, which alone is impressive and reason enough to consider them as a PSU for a desktop. They also claim the units are able to provide clean power even under heavy load, which is critically important for high end systems:
With Active Power Factor Correction (PFC) circuitry providing a PF value of 0.99 under full load and 80% or more energy efficiency under a wide range of loading conditions, the TX Series of power supplies generates minimal heat during operation. The high quality thermally controlled double ball-bearing 140mm fan (120mm on 650W) delivers excellent air flow with whisper quiet operation.
While somewhat pricey, they aren't so expensive as to make them out of reach. The MSRP on these is $180 and $200 for 650W and 750W respectively. PSUs have been and remain perhaps the single most important component of a system. That's becoming even more true now when seeing dual video cards and dual or quad core processors in a system that draw more power than ever before. You can read the full press release in the comments section.