I was running into problems when I tried to install Visual Sourcesafe 2005 (VS2005) on Windows 8 (64-bit) environment. And yes, I know, Sourcesafe is out-dated, but I still have to use it :(.
Anyway, I searched around but didn't find a solution. So I tried it myself to work something out, and with luck (and it is actually something stupid easy...)
Just start the setup.exe of vs2005. You will run into the window 'Program Compatibility Assistant' (PCA), click on the option 'Run the program without getting help'.
You will get this PCA-window a couple of times, just continue clicking 'Run the program without getting help'. Finally you get in the ordinary installation procedure of VS2005 and you can install it as normal.
Once installed, it just works fine!
Edit: If it doesn't work, just verify if .NET framework 2.0 and 3.5 are installed (thanks Suren!)
Happy programming folks!