PHP != and == operators

This has boggled me for a while. I am running through a directory and echo'ing out its contents, and I want to exclude the ".." and "." files.

Now, this code works:

if ($files = scandir("temp/"))
{
    foreach ($files as $file)
    {

        if ($file == ".." OR $file == ".")
        {
        }
        else {
            echo $file;
            echo "
";
        }
    }
}

But this doesn't...

if ($files = scandir("temp/"))
{
    foreach ($files as $file)
    {
        if ($file != ".." OR $file != ".")
        {
            echo $file;

            echo "
";
        }
    }
}

For obvious reasons the second lump of code is more what I want, because I really hate having the true statement do nothing.