I agree with Asad, it can be dodgy making assumptions based on the user's browser language preference. Some sites do this kind of thing and it is possible to implement it in a custom UserControl that you would include in your layout.master, but it would require a good bit of thought to avoid problems. You want the user to feel in control at all times and avoid unexpected experiences.
For example you would only want to do the redirect on the first request and only if the request is for your home page. So you would want to set a cookie before you redirect so that on the next request you can detect the cookie and know that you already redirect one time so don't redirect again if the user comes back to your main language site. There could be problems if the user's browser does not accept cookies then you would end up redirecting on every request. Of course you would have to decide also based on whether you have a site created for the user's language and also consider that the browser language can be an array of languages, probably the lowest index is the most preferred language. You would need to be careful to avoid errors if the language cannot be detected. There are lots of bots and spiders that may not indicate a language.