V1.5 has been superceded by a number of other versions. The latest is V2.0.4, which is at http://support.slingbox.com/go/windows-download-desktop-us
But I would try and find a copy of V1.5 if you can, because V2.0 removed the Custom Button option so if you use that you might want to stick with V1.5. V2.0 also relies more heavily on the SLing servers, and that caused havoc last Septemeber and only V1.5 worked. But give 2.0.4 a try first.