If you are using ActiveState perl (update: Ahh, I see you are), then Win32::Process is part of the standard distribution. You would create another perl process something like this:

Win32::Process::Create(my($procobj),
  "C:\\Perl\\bin\\perl.exe",
  "perl C:\\path\\to\\another_perl_script.pl",
  0,
  NORMAL_PRIORITY_CLASS|CREATE_NO_WINDOW,
  ".", # path to working directory
) or die ErrorReport();
[download]

The third argument is supposed to be command line arguments, but for some reason you have to include 'perl' as well as any arguments. See the Win32::Process docs for the ErrorReport() function (which basically just regurgitates $^E).