Dcom:
SUMMARY
The Distributed Component Object Model (DCOM) is a protocol that enables software components to communicate directly over a network. Previously named "Network OLE," DCOM is designed for use across multiple network transports, including Internet protocols such as HTTP. More information about DCOM, visit the following Microsoft Web site:
http://www.microsoft.com/com/tech/dcom.asp (http://www.microsoft.com/com/tech/dcom.asp)
DCOM is supported natively in Windows NT 4.0, Windows 2000, Windows XP, and Windows Server 2003.
Warning If you disable DCOM, may you may lose operating system functionality. After you disable support for DCOM, the following may result:
• Any COM objects that can be started remotely may not function correctly.
• The local COM+ snap-in will not be able to connect to remote servers to enumerate their COM+ catalog.
• Certificate auto-enrollment may not function correctly.
• Windows Management Instrumentation (WMI) queries against remote servers may not function correctly.
There are potentially many built-in components and 3rd party applications that will be affected if you disable DCOM. Microsoft does not recommend that you disable DCOM in your environment until you have tested to discover what applications are affected. Disabling DCOM may not be workable in all environments
RPC Locator is set to manual by default in SP2 (could even bp SP1 I cant remember)
Netbios may or may not be needed - depends on your network setup.
AFIAK the initial upnp holes have been plugged, but unless you have a upnp device on your network theres no reason to have upnp enabled
messenger ervice, unless you want to send local meeages using netsend or any 3rd party variants, then disabling is fine