Localized Windows Versions

In Windows XP/Vista, I want to know if I can change everything, the dialog boxes, the file, edit, view, etc menus, literally everything (or almost everything) that's in English to another language. Is this possible without buying a localized version of Windows in the language that I want? I googled around but all I got was very vague descriptions of "frameworks" and "APIs" and "technologies."

Thanks in advance!

JUST EDIT THE SOURCE CODES

No. you need localised versions. yet another problem with closed sauce.

Recompile your kernel with --with-LANGUAGE where LANGUAGE is your favourite localization.

LANG=wa_WP.UTF-8 opera