I'm pretty sure that you wouldn't want to be able to do that from javascript either. Javascript runs in the client's browser, so you shouldn't be able to escape to execute some other app. If you could get IE to open from Netscape, that would basicly also allow you to execute anything you wanted to on the visitor's computer!

And what if your visitor doesn't have IE ? There are people browsing the web on their cell phones these days...

When people talk about browser redirection, they are mostly describing the use of CGI to detect the useragent and redirect the visitor to a site customized for that browser. You could detect old browsers and send them to a plain text layout, and send more up-to-date browsers to your CSS & Javascript extravaganza. You wouldn't even have to code the pages twice if you used some sort of templating system to generate the pages for you.