Running Drupal in a Windows environment (IIS, SQL Server)?
Easiest way is to use the Microsoft Web Platform Installer to install Drupal 7 - http://www.microsoft.com/web/downloads/platform.aspx

The only option it currently provides is using SQL Server as the back-end database, so you should be golden. (The Drupal 6 WebPI installs do not target SQL Server)

I've been running Drupal 7 on a Hyper-V-based VM under Win2k8 R2 with SQL Server Express as the backend DB for a few weeks without incident.