This is something that anyone interested in BizTalk 2004 should look at...

14 Free on-line BizTalk Server 2004 Hands-on labs available

14 BizTalk Hands-on Labs are now publicly available in the full-featured MSDN Virtual Lab at: http://msdn.demoservers.com/login.aspx?group=biztalk  
See the following for details: http://blogs.msdn.com/sspotts