Thanks for the response. Here's the update code we run after a successful mssql_connect (to load $connection) and mssql_select_db. We run the statement and it dies with the "Couldn't execute query message". When we run the statement from another box (using NT/php4.02) it works.
$sql = "UPDATE users SET first_name = '$first_name', last_name = '$last_name', dept_id = '$dept', reports_to = '$verified_reports_to', title = '$title', email = '$email', hire_date = '$hire_date', birthday ='$birthday', phone_number = '$phone_number', location_id = '$location', travel_switch = '$travel', employment_status = '$employed', reports_to_id = '$reports_to_id' WHERE user_id = '$id'";
$sql_result = mssql_query($sql,$connection) or die ("Couldn't execute query.");