UNABLE TO CONNECT TO MY MS SQL DB

I have just installed your Tools extension, but cannot connect to my database to retrieve my data.

It fails with this message:

JError: Unable to load Database Driver: mssql

I have tried various combinations of database type. host, user etc, but same very time. Basic settings have been:

Database Type: mssql
Database Host: <ip address of local lan server>
Database User: sql user login
Password: sql user password
Database Name: <name of db>

As soon as I click 'Check and List Tables', I get the error

My Joomla instance is running PHP 5.3.13, and the MS Sql Server is 2008

I followed a procedure on here to load drivers but it does not work - when I try to run php it tells me that the dll is not a valid win 32 application

Which driver should I load ?

And which procedure do I follow ?

Do you not have official documentation telling Customers how to do this ??

Windows Server 2012 Standard - with Joomla running under WAMP