Those are not Windows specific codes, they are unicode values and quite standard and unambiguous, and the Right Way To Do It.
If you have a font anywhere on your system that includes those codes your browser will use it. For any code that your browser can't match in any of the available fonts, obviously there's nothing it can do.

They all work on my Linux system - but I have a lot of fonts installed, including a bunch of Windows TTFs copied over from an MS Office installation.

Anahata