Cody,
My setup is almost identical to yours, and I get no results either. Just one row with the value NULL. (I think blank lines get returned as NULL when using xp_cmdshell, based on testing with the DIR command). I originally was using SETSPN.EXE version 5.00.2184.1, but downloaded the newest version, 5.2.3630.0. Didn't make any difference. Other commands work fine (like dir *.*, etc) and return results. I logged onto 2 of my servers to test this, and it doesn't work locally either.
Microsoft released PRB regarding the failure of the file compare utility (FC) when run with xp_cmdshell, but that program works for me.
I still find it interesting that even from a command window, the output cannot be redirected to a file.
Mike