Cabioman,
Previous versions of Project were downloaded either as an EXE or DMG file format that could be opened directly for installation. However, Project is now provided as an IMG file that either must be converted or used to burn a DVD. I'm assuming you can't start
it because you are trying to open the IMG file directly. There are multiple conversion utilities available. For example, try the following link: http://softadvice.informer.com/How_To_Open_.img_File_Windows_7.html
This issue has been raised several times on this forum. A search for "open trial version" will get you several previous answered posts on the subject.
If you are running Windows 8 (I am not) , it is my understanding that Windows 8 has the necessary conversion built-in. Just search for it.
Hope this helps.
John