Split the windows build requirements by version

docs/build-instructions/windows.md

@@ -2,12 +2,23 @@
 
 ## Requirements
 
-  * Windows 7 or later
-  * [Visual C++ 2010 Express](http://www.visualstudio.com/en-us/downloads/download-visual-studio-vs#DownloadFamilies_4) with [SP1](http://www.microsoft.com/en-us/download/details.aspx?id=23691)
+### On Windows 7
+  * [Visual C++ 2010 Express](http://www.visualstudio.com/en-us/downloads/download-visual-studio-vs#DownloadFamilies_4)
+  * [Visual Studio 2010 Service Pack 1](http://www.microsoft.com/en-us/download/details.aspx?id=23691)
   * [node.js](http://nodejs.org/download/) v0.10.x
+    * For 64-bit builds of node and native modules you **must** have the
+    [Windows 7 64-bit SDK](http://www.microsoft.com/en-us/download/details.aspx?id=8279).
+    You may also need the [compiler update for the Windows SDK 7.1](http://www.microsoft.com/en-us/download/details.aspx?id=4422)
+
   * [Python](http://www.python.org/download/) v2.7.x
   * [GitHub for Windows](http://windows.github.com/)
 
+### On Windows 8
+  * [Visual Studio Express 2013 for Windows Desktop](http://www.visualstudio.com/en-us/downloads/download-visual-studio-vs#DownloadFamilies_2)
+  * [node.js](http://nodejs.org/download/) v0.10.x
+  * [Python](http://www.python.org/download/) v2.7.x (required by [node-gyp](https://github.com/TooTallNate/node-gyp))
+  * [GitHub for Windows](http://windows.github.com/)
+
 ## Instructions
 
   ```bat