use strict;
use warnings;
use Win32::Process qw();

my $app = "$ENV{SystemRoot}\\Notepad.exe";
my $cmd = 'Notepad "my file.txt"';
my $proc;
my $flags = Win32::Process::NORMAL_PRIORITY_CLASS();
my $startDir = 'c:\\tmp';

Win32::Process::Create($proc, $app, $cmd, 0, $flags, $startDir);