Win7 Home Premium can't change the UI language. You need Enterprise or Ultimate to do that, or a fresh install of Windows (though I can't remember whether you can just select the language during install; if you can't, you'd need a separate install disc for English)
I hadn't known about that program, but I'm a little worried about it circumventing the normal requirement of having the Enterpise or Ultimate edition to do that. That might lead to technical or legal problems down the line.
Edit: Ronnie Vernon's answer on the page that SR-71 Blackbird linked confirms that using that program will invalidate your Windows license and activation.