Actually Kavan they're correct.
The student teacher edition is not a separate build of Microsoft Office, it is just marketed differently, costs less and has some bits taken out.
Microsoft released Office X when OS X was released and then Office 2004. During the interim period they were selling Office X and it would have the copyright dates for the year the disc was made ie 2003. If you had an Office X disc from 2002 it would say 2002.
You don't have to take my word for it. You can look at the Microsoft Mac site here. You will see there was no Office 2003 for the mac, and if there had been, Microsoft would have called it Office 2003 for Mac, as they did for Office 2004.
http://www.microsoft.com/mac/otherproducts/otherproducts.aspx?pid=otherproducts
Anyway, should be fine under Rosetta. Good luck.