private void Form1_Load(object sender, EventArgs e)
{
    if (!IsWin7())
    {
        Application.Exit();
    }
}
bool IsWin7()
{
    return Environment.OSVersion.Version.Major == 6 && Environment.OSVersion.Version.Minor == 1;
}
bool IsWinVista()
{
    return Environment.OSVersion.Version.Major == 6 && Environment.OSVersion.Version.Minor == 0;
}