My SQL Server code tends to look something like this:

use strict;
use DBI;

my $database = 'northwind';
my $login = 'sqluser';
my $password = 'sqlpw';
my $host = 'OURSQLSERVER';

my $data_source = "dbi:ODBC:driver={SQL Server};Server=$host;database=
+$database;uid=$login;pwd=$password;";
}
[download]

<update>IIRC you need to install DBD::ODBC - and I'm assuming you're running your perl on a Win OS...</update>