Windows Server 2003 SP1

Download this massive Service Pack for WinServer 2003...
A single update which includes all the latest patches
http://www.microsoft.com/downloads/details.aspx?familyid=22CFC239-337C-4D81-8354-72593B1C1F43&displaylang=en

Take a look at more details:
http://msdn.microsoft.com/security/productinfo/Server2003/default.aspx