I've just read this thread and I'd like to ask you some questions:
1. Is your Moodle installation going to be accessed via Internet or it is just going to be used internally?
Sometimes is better and easier to use a shared hosting provider when one needs to set a Web app online.
2. Is it mandatory to use the "Microsoft Web Platform Installer with Moodle" package, or it was chosen only because it would simplify the Moodle installation?
Complete package installers are usually easy to use, but sometimes they can fail for one reason or another. You must be aware that complete installers are usually best for learning, testing or development, not for production (going alive).
3. If you don't have any particular restrictions about the installer, do you have any about the web server, that is, IIS vs. Apache?
You might want to take a look at:
* Install Moodle 2.0 on Windows Server 2008/R2 with MySQL, as it explains in a clear manner how to install the Web Platform Installer. The author didn't use the Moodle package from the Web Gallery, but used a Standard Moodle Package (from moodle.org).
* The Windows installation docs.
If you only need your Moodle installation for learning, testing and/or development, you could also try using either of the following:
* Windows Moodle Distribution
* BitNami Moodle Stack
Both use the Apache HTTP Server.