I'm always asking for and searching for help in places like this, especially because we host Wordpress (and now WPMU!) on Windows servers!
Hopefully this will help other people that want to run Wordpress MU on Windows. We used Wordpress MU Version 2.8.6 and are running IIS 7 on Windows Server 2008.
I'm just going to tell you how we got WPMU running, not how to install PHP and MySQL and all that stuff. There's plenty out there about that, but less about this specific topic:
How to Install Wordpress MU on IIS 7
Download Wordpress mu
Extract and copy into desired directory on IIS 7 web server
Give IUSR user account modify and write permissions on the directory in IIS
Create database and user with all permissions to use it in MySql
Navigate to the location of your site (where your files are stored on IIS)
Enter the required information in the mu installation screen – make sure your server address isn’t a single word – such as ‘mysite’, use ‘mysite.com, even if your mu installation is internal. We tried installing our site at ‘mysite’ for testing purposes, everything worked as described below, except we couldn’t log into the admin side using Firefox or IE 8 – only safari could log us in, something to do with the cookies used to process login.
We used sub-directories, we couldn’t get sub-domains to work.
Enter all the other details on the mu installation screen as expected, then press install.
We got a 500 Internal Server Error, but not to worry, everything’s been created!
Normally the admin password would be e-mailed to the address you entered on the previous screen, but in our case it wasn’t (on-going issues with the php mail function and receiving mail to our Exchange 2007 Server).
What we did to get round this was to go into the database in phpMyAdmin and manually change the password (user_pass field in the wp_users table) to one of our choosing, but be sure to use the ‘md5’ function to encrypt your password before you update your table.
Go back to your server address to see the home blog running as it should.
Log in with the ‘admin’ user and the password you’ve just set.
We didn’t have to make any changes to get pretty permalinks working (I’m sure you would on IIS 6 though – they seem to be the default option with mu. What we did do though is remove /blog/ from the permalink structure under Blog > Edit. I don’t know why this was added by default, but we don’t want it, so removed it. We for some reason it didn’t work the first time we navigated to a page, we got the not found error, although the link we tried was pointing to the correct location – without /blogs/
We can now create and manage as many blogs as we like (sub sites actually) and we’ve even got the WPDirAuth plugin working with them.
Hope this helps someone.