Is there a way to use the Intel GPU when running Windows 7 from Bootcamp?
This accepted answer is no longer correct for newer models. Newer Macs don't let you use the Intel Graphics Card on Windows. Here is a thread with explanations and a really complicated workaround.



For older Macs: 

Let's start with this from Intel.

Then go here and select the right driver.

 EDIT: Since we still have the problem lets go back to BASICS:

What do I need to install Windows 7?

This table shows the required Bootcamp version.

Try removing application receipts:

If you're reinstalling an application or updating an existing one, try removing the application's receipts. Look for any receipts that bear the name of the application in the the Receipts folder inside of the main Library folder (/Library/Receipts) and move them elsewhere. Then try installing or updating your software again.