Put file1 in a component being installed to dir1 and give it a condition of SystemLanguageID=1033.
Similarly with the other files in their own components.
http://msdn.microsoft.com/en-us/library/aa372056(v=vs.85).aspx
In a per user install it could make more sense to use UserLanguageID in case the user is using one language and the OS is another.
http://msdn.microsoft.com/en-us/library/aa372384(v=vs.85).aspx