Silly question: How to tell if I have a legal copy of 2003?

I work for a company that installs and ships our software on windows 2003 server systems. Recently, we took weeks configuring a system that turned out to be based on a non-shippable (as in, an MSDN) copy of 2003. So now I'm doing it all over again -- but going forward, how can I tell the difference without running Sysprep (as i did before)

is the information hidden in a reg key? If so, where is that dog?

thanks

 

If it's a non legit copy there are some messages that show up in the event logs. It's been a while since I have seen one so I can't say exactly what the message was.