It is now possible to install Drupal 7 with MS SQL server but it requires some works!
The steps are:
. If you want to use friendly URL, install URLRewrite module in IIS to take advantage of the support of URLRewrite in Drupal 7 from here: http://www.iis.net/download/URLRewrite
. Install the PHP SQL Server Driver 2.0 from here: http://www.microsoft.com/downloads/en/details.aspx?FamilyID=80e44913-24b...
. Create a Drupal database and user login and password in SQL Server. (Please note the "instance" name which you will need when doing the install)
. Download and uncompress Drupal 7 in your web space
. Download Drupal SQL SRV module from here: http://drupal.org/project/sqlsrv
. Uncompress and put in this folder: sites/all/modules/SQL SRV
. Copy the schema folder from sqlsrv/*.inc to this folder includes/databases.
. Install Drupal as you normally would but the database info as follow:
+ hostname: Please enter something like: 'YourSQLserverName\SQLInstanceName'. If you're configuring this in settings.PHP, it would be 'YourSQLserverName\SQLInstanceName'.
+ username: It is a SQL Server "login" that you must create and map to a SQL Server user.
That's it!
Here is an easier way if you are using Microsoft Web installer for Drupal which you can get from here: http://microsoft.com/web/drupal