In windows Perl can be installed in any directory or hard drive on the system, you can have many different versions of Perl installed also.
When you install ActiveState Perl or Strawberry Perl on windows the installer should allow you to pick the location to install Perl to, the installers also likes to add the path to Perl in the windows environment variable "PATH". This gives your Perl script the ability to use the shebang #!perl otherwise if there is no environment variable for the Perl version you want to run. Then you will need to set your shebang to the full path to the Perl interpreter you want to use like #!C:/Perl/bin/perl.exe
The windows environment variable's read from top to bottom or from left to right and will only use the first "PATH" to Perl it reads, some windows versions let you move environment variables around so you can keep a copy of it. Not all uninstallers will remove the environment variable, so that can cause a problem.
Good Luck,
