use Win32::ChangeNotify;

my $dir = "c:/some/dir/name";

$notify = Win32::ChangeNotify->new($indir, 0, FILE_NAME);

while (1)
{
 $notify->wait or warn "Problem waiting: $!\n";
 # Will now wait to execute following code
 # until a file event happens in $dir

 # ...stuff ...

 $notify->reset;
}
$notify->close;