You need to select the GTA SA folder inside RockStar games, not just the root rockstar games folder.
"Can't install".. What do you mean by this; You can install samp to C:\ILoveSAMP\ if the folder exists; it'll install it anywhere is my point. Are you getting an error? If you are getting an error you will most likely need one of the following.
http://www.microsoft.com/download/en...s.aspx?id=5555 x86
or
http://www.microsoft.com/download/en....aspx?id=14632 x64
These should most likely already be installed if you use Windows Update, however fresh installs/lacking the update button can create a problem. This is normally only a server problem; however can still be a cause.
If you are getting an error and you use Windows Vista or Windows 7 try running as administrator.
If you are using Windows 8, this could be a driver issue or some sort of C++ error in the latest build.
While by the way you are describing it. It doesn't seem like a problem with SA:MP, or the GTA files.
Hope it helps
- Teddy