Though it may be obvious to most here, as simonm pointed out in his update. No where in the module does it say it is for only Win32 systems and some win32 modules imply that they are working on working on running on across systems, even though the functionality is windows based as this quote from Win32::TieRegistry:

Win32::TieRegistry - Powerful and easy ways to manipulate a registry on Win32 for now.

But if yfou go to the base Win32 README:

This used to be a bundle of extensions that provided a quick migration path for people wanting to use the core support for win32 in perl 5.004 and later. With the release of Perl version 5.005 (which brings ActiveState's changes to Perl sources into the mainstream), this library of extensions has assumed loftier motives. The long term goal of this project is to provide a coherent collection of modules that allow access to the functionality provided by the Win32 API, while maintaining the style and spirit of Perl. Like Perl, the intention is to make "easy things easy, and hard things possible". Note that we are nowhere close to this goal at the present time, but we are slowly getting there. As the name suggests, all modules in this distribution are Win32-specific. They cannot be used on platforms that do not support the Win32 API.