check your nativ language

how i can determine the user languagewhich installed in his operating system to link him to the site in his languge

Try to inspect these data:

var t=0;for(var i in navigator){t+="\n"+navigator[i]+" "+i}+i;alert(t)

on IE yields:
navigator.systemLanguage
and
navigator.userLanguage

are your lot.

On NN4 and NN6 both
navigator.language

seems carrying the info you want, obviously all as shortcuts: en for english, it for italian, and so on....