Can't connect to sql with php!?

Hi, I posted this in PHP also, because I wasn't sure if it was a php or sql problem.

I can't get my code to connect to the SQL Server 2005 database. My code is very simple:
<?php
$ConnString='DRIVER={SQL Server};SERVER=sql2k512.discountasp.net;DATABASE=SQL2005_etc';
$DB_User='SQL2005_etc_user';
$DB_Passwd='PASSWORD';
$Connect = odbc_connect($ConnString, $DB_User, $DB_Passwd) or die ('Unable to connect to database');

if($Connect){
echo 'yay';
}
?>

Every time I try to go to that page, it just says:
Warning: odbc_connect() [function.odbc-connect]: SQL error: [iODBC][Driver Manager]Data source name not found and no default driver specified. Driver could not be loaded, SQL state IM002 in SQLConnect in /Library/WebServer/Documents/hudpro/test/test_connect.php on line 5
Unable to connect to database


Any help would be appreciated. I'm completely stuck and have an approaching deadline! Thanks!