Try this:
Download the software, and extract the file, next open the zune package, and go to the x64/x86(whichever you use) folder, next go to Packages, then download Orca, and install it on you computer, then go back to the Packages folder and right click the file that says zune-x64/x86.msi and open it with Orca, then go to Launch Condition and right click the second row and choose drop row, then save, and launch the zune-x64/x86.msi file and it should install without problems.
Ocra Download