How about something like this? It is mostly a copy/paste from the Win32::DirSize synopsis. I have tested this on my Windows 7 laptop after installing it with ppm install --force http://www.bribes.org/perl/ppm/Win32-DirSize.ppd (a cpan install of the module failed).

use strict;
use warnings;
use Win32::DirSize;

my $path = "\\\\domain.local\\users";

y $result = dir_size( $path, my $DirInfo );

if ( $result == DS_RESULT_OK )
{
    print "Dir size is $DirInfo->{DirSize} bytes\n";
    print "Dir size on disk is $DirInfo->{DirSizeOnDisk} bytes\n";
}

if ( @{ $DirInfo->{Errors} } )
{
    for my $Error ( @{ $DirInfo->{Errors} } )
    {
        printf( "Error #%d at %s\n", $Error->{ErrCode}, $Error->{Locat
+ion} );
    }
}
[download]