Where do I get the correct Boot Camp Support Software for my machine?
If you follow the links given in this tutorial, you will find the drivers for your Mac can be downloaded from the Apple website Boot Camp Support Software 4.0.4033. If you are installing 64 bit Windows 7, 8 or 10, then you can follow the instructions given as the accepted answer to the question Using Boot Camp Support Software 4.0.4033 to install 64 bit Windows 7 or 8.