Is there a way for me to open a .xdi file? I have on my computer a file that as been compress with the .xdi extension.

Is there a way for me on my Mac OS X to open it?
If you absolutely have to use a Mac to open the xdi file, and you have Parallels or some other virtual environment that can run Windows, you can install WinArchiver and open the file that way.

As far as I know there is no utility for Mac that can open xdi files because they are created using WinArchiver which is a Windows only app.