This is the easiest way to install Digby's Donuts. All you need to do is choose "Open" when prompted and then follow the instructions to install Digby's Donuts to your computer.
Choose this option if your network doesn't allow direct downloading of executable files. Once downloaded, extract the zip file and run digbysdonuts.exe, which will install Digby's Donuts to your computer.
If neither of the above options work for you, try these:
