I beleive you have two problems. First the one mentioned above, about your single quoted filename, and second that you should be using Path instead of filename. The script below seems to work fine for me.

#!/usr/bin/perl -w
use MIME::Lite;
use Net::SMTP;

$msg = MIME::Lite->new(
                        From    =>'root@mycompany.com',
                        To      =>'me@home.com',
                        Subject =>'Summary Report',
                        Type    =>'multipart/mixed'
                       );

$msg->attach(
                        Type => 'TEXT',
                        Data => 'Test Message'
);

$msg->attach(
                Type       =>'TEXT',
                Path       =>$path
            );

$msg->send('smtp','localhost');

exit 0;
[download]

HTH