You can use the Win32::OLE::NLS module to access the Windows National Language System stuff. For example:

    use strict;
    use Win32::OLE::NLS qw(:DEFAULT :LOCALE);

    my $lcid = GetSystemDefaultLCID();
    print GetLocaleInfo($lcid, LOCALE_SLANGUAGE);
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It also provides you with localized dates, times, money etc (in combination with Win32::OLE::Variant).