Automatically Change IE Proxies

I need a **vb.net app** that can use and auto-change proxies for Internet Explorer 7 and later. I use the WinNet dll and edit the registry to achieve this but doesn't work on every computer. I need another method of accomplishing this consistently on Windows XP, Vista and 7. If you know of another better method please place you bid, and maybe send me a demo if possible. Or if you know how to use Winnet dll quite well to achieve this, please place your bid.