Make the programs work on a specific windows version

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;
}

others windows versions:
Server 2008 R2
Major=6
Minor=1

Server 2008
Major=6
Minor=0

Server 2003
5
2

XP
5
1

2000
5
0

NT4
4
0

ME
4
90

98
4
10