Wanna know the Schema version of your Active Directory?
One simple way is to logon to a domain controller and go to HKLM\System\CurrentControlSet\Services\NTDS\Parameters and look at the data portion for
the "System Schema Version" entry which sometimes, in some situations of which I'm not aware of but I've heard on the street, it's called the "Schema Version" entry.
Then check it against the following:
13 = 2000
30 = 2003
31 = 2003 R2
44 = 2008
?? = 2008 R2
Is there a pattern that I'm just not seeing?
--UPDATE--
You can look in ADSIEdit too. Just look at the objectVersion in the properties of CN=Schema,CN=Configuration,DC=your,DC=domain,DC=com.