how can I install Drupal 7 with PHP 5.2 on a Windows Server 2003 machine with IIS 6.0 and SQL server 2000 running on it?
I am not sure why you are using SQL2000 in 2014 because it is not supported anymore. 
I have successfully connected to SQL 2008 version using SQLSRV module in Drupal. 

I would do the following in this case:


Make sure TCP\IP protocol is enabled and it is listening on some port which is not getting blocked by firewall.
I would try connecting to the database server using IP address and port using enterprise manager first.
I would look in my SQL error logs because it records the authentication failures there.


Please share what you observe.

Thanks
C