Based in part on Tomas Petricek's instructions here and here.

1. Either
   1. Install Visual Studio 2008+ (Which you may already have installed).
   2. Or download and install the .NET framework 3.5+ here: http://msdn.microsoft.com/en-us/netframework/aa569263
2. Download and install Gtk# for .NET here: http://monodevelop.com/Download
3. Download and install MonoDevelop for Windows here: http://monodevelop.com/download
4. Either
   1. Install Visual Studio 2010+ (Which ships with F#) and select the F# option during setup or modify your existing installation to include F# (via Control Panel | Programs and Features | Microsoft Visual Studio...)
   2. Or install the F# stand alone package here: http://www.microsoft.com/downloads/en/details.aspx?FamilyID=f8c623ae-aef6-4a06-a185-05f59be47d67
5. Install the F# MonoDevelop language bindings
   1. In MonoDevelop, click Tools | Add-in Manager and click the "Install Add-ins..." button.
   2. Next click the "Repositories..." button, then the "Add" button.
   3. Make sure the "Register and on-line repository" radio button is selected and enter http://functional-variations.net/addin/ and click "OK".
      
      
      
   4. Close out of the "Add-in Repository Management" dialog, expand the "Language bindings" node, check the "F# Language Binding..." and click "Forward". 
      
      
      
   5. Click through default options in the add-in installation and restart MonoDevelop after it completes.
   6. Now you should see the F# project and file templates when creating new file or project.