1. Interop Services?

The common language runtime provides two mechanisms for interoperating with unmanaged code:
Platform invoke, which enables managed code to call functions exported from an unmanaged library.
COM interop, which enables managed code to interact with COM objects through interfaces. Both platform invoke and

COM interop use interop marshaling to accurately move method arguments between caller and callee and back, if

required.

2. How does u handle this COM components developed in other programming languages in .NET?

3. What is RCW (Runtime Callable Wrappers)? The common language runtime exposes COM objects through a proxy called

the runtime callable wrapper (RCW). Although the RCW appears to be an ordinary object to .NET clients, its primary

function is to marshal calls between a .NET client and a COM object.

4. What is CCW (COM Callable Wrapper) A proxy object generated by the common language runtime so that existing COM

applications can use managed classes, including .NET Framework classes, transparently.

5. How CCW and RCW is working? 

6. How will you register com+ services? The .NET Framework SDK provides the .NET Framework Services Installation

Tool (Regsvcs.exe - a command-line tool) to manually register an assembly containing serviced components. You can

also access these registration features programmatically with the System.EnterpriseServicesRegistrationHelper class

by creating an instance of class RegistrationHelper and using the method InstallAssembly

7. What is use of ContextUtil class? ContextUtil is the preferred class to use for obtaining COM+ context

information.

8. What is the new three features of COM+ services, which are not there in COM (MTS)?

9. Is the COM architecture same as .Net architecture? What is the difference between them? 

10. Can we copy a COM dll to GAC folder?

11. What is Pinvoke? Platform invoke is a service that enables managed code to call unmanaged functions implemented

in dynamic-link libraries (DLLs), such as those in the Win32 API. It locates and invokes an exported function and

marshals its arguments (integers, strings, arrays, structures, and so on) across the interoperation boundary as

needed.

12. Is it true that COM objects no longer need to be registered on the server? Answer: Yes and No. Legacy COM

objects still need to be registered on the server before they can be used. COM developed using the new .NET

Framework will not need to be registered. Developers will be able to auto-register these objects just by placing

them in the 'bin' folder of the application.

13. Can .NET Framework components use the features of Component Services? Answer: Yes, you can use the features and

functions of Component Services from a .NET Framework component.

http://msdn.microsoft.com/library/techart/Pahlcompserv.htm