Windows 2003 ACL
http://www.microsoft.com/windowsserver2003/howtobuy/licensing/caloverview.mspx
Windows 2003 Edition Comparison
http://technet.microsoft.com/en-us/library/cc758523.aspx
SQL Server 2005 Licensing
http://www.microsoft.com/sqlserver/2005/en/us/licensing.aspx
SQL Server 2005 is available under three different licensing options: per processor or per server plus device/user client access licenses (CALs)
(Source: http://www.eit.name, admin.net[(at)]163.com)
SQL Server Multicore Licensing Policy
http://www.microsoft.com/sqlserver/2005/en/us/Special-Considerations.aspx
Oracle Licensing
http://www.orafaq.com/wiki/Oracle_Licensing
Oracle multicore licensing
http://www.oracle.com/corporate/press/2005_dec/multicoreupdate_dec2005.html
Oracle Edition Comparison
http://www.oracle.com/database/product_editions.html