Hi,
I glad to say that the AD7781EVB works with windows 7.
in the user guide ( and the EVB software ) its mentioned to remove LK1 to LK4,
doing that disconnect the load cell from the excitation voltage.
I kept LK3 and LK4 and removed LK1 and LK2 and it works.
another thing,
trying to open the schematic file from http://www.analog.com/CN0108-DesignSupport
with Orcad resolves with a file error message.
can you send me please a schematic file that works?