If you want to view the current version of your Active Directory you have, you can browse to the following registry key on your domain controller(s).
HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\NTDS\Parameters and select the subkey Schema Version.
13 = Microsoft Windows 2000
30 = Original release version of Microsoft Windows Server 2003 and Microsoft Windows Server 2003 Service Pack 1 (SP1)
31 = Microsoft Windows Server 2003 R2
44 = Windows 2008