File structure for Due in Windows 7 (WDT again.)

Specifically I am trying to run the watch dog timer (WDT) on the Due. I need to remove the disableWDT command in the Arduino core.

What is the file structure for the Arduino software running IDE 1.6.7 (latest version) in Windows 7?
Are the files for the SAM3X8E (Due) just mixed in with "avr" or are they seperate?

Previous WDT forums refer to path ...hardware\Arduino\Sam... I assume that this is Linux because I can't find this path in Windows.

The only reference I can find for the WDT is wdt.h. Looking in that file I see many sections relating disableWDT. However, I can find no reference to the SAM3X8E chip. Perhaps it is under an equivalent, but different, name. Any help appreciated. Thanks.