@Sigurd: here is how my SS install on IIS 7 has progressed so far. I followed the steps from the documentation, and copied the web.config verbatim.

Received the following error:

PHP Warning: file_exists() [function.file-exists]: open_basedir restriction in effect. File(../../_ss_environment.php) is not within the allowed path(s): (C:\inetpub\wwwroot) in C:\inetpub\wwwroot\sapphire\core\Core.php on line 31 PHP Warning: file_exists() [function.file-exists]: open_basedir restriction in effect. File(../../../_ss_environment.php) is not within the allowed path(s): (C:\inetpub\wwwroot) in C:\inetpub\wwwroot\sapphire\core\Core.php on line 31 PHP Fatal error: Permission problem gaining access to a temp folder. Please create a folder named silverstripe-cache in the base folder of the installation and ensure it has the correct permissions in C:\inetpub\wwwroot\sapphire\core\Core.php on line 230

I tried creating the folder "silverstripe-cache" and refreshed, but get a looong list of files it cannot open with the error "Permission Denied"

So, I opened php.ini and "commented out" the "open_basedir" line, restarted IIS, **and** deleted the "silverstripe-cache" folder.

Now I get the SS install screen.

According to the documentation at http://doc.silverstripe.com/doku.php?id=iis-installation I am suppose to delete the .htaccess file before loading up http://localhost//install.php but if you do that, the SS complains that the .htaccess file is not writable. So I am leaving it in place until after the install.

Enter the MySQL details, admin account, everything looks good except for "warnings" about "allow_call_time_pass_reference" and not being able to tell if mod_rewrite is running.

Click on Install and get the "generic" Windows 500 Internal Server Error.

An interesting side note (maybe a good clue, actually), is when I try and load it from a different computer via the public IP address, it tries to re-direct with a backslash included. E.g., http://192.168.168.168 tried to send me to http://192.168.168.168\/install.php and the browser complains about a bad address.

I am going to try a "manual" install.

Thanks again for the assistance everyone!

There is an update at http://silverstripe.org/installing-silverstripe/show/255574?showPost=255574