Just ignore the "best answer" in that thread. WEI is a horrible indicator of system performance and this insanely stupid idea that wattage is so important is vastly overrated.
Simply put, a GTX460 will in fact run on a DG41RQ, but with the possibility or a slight performance hit from the PCIe 1.x bus. PCIe x16 provides the same bandwidth as PCIe 2.0 x8. PCIe 2.x cards are backwards compatible with PCIe 1.x systems.