It seems that you are having some issues in order to set up your Slingbox SOLO on a Windows 7 computer.
Since you have not included the information about the Direct TV box, I recommend you to check this link. It will allow you to determine if your box is included on the supported devices list.
If it is included, you only need to follow the on-screen instructions. If not, you can check the following thread, provided by alanrichey42.