Install Drupal with MS SQL Server 2008 R2 Is it possible in any ways to connect Drupal 6.x to MS SQL Server 2008 R2 on Windows Server 2008? I am really struggling to find a way out.

please let me know. Any help would be greatly appreciated!
The requirements clearly states that the supported databases in Drupal 6 are "MySQL 4.1 or higher, PostgreSQL 7.1."

You would have to write the database support yourself to get this working.

Drupal 7 does support MS SQL Server however.