Difference between "traditional" COM and COM+ (in Component Services)

COM+ (Component Services) provides a lot of infrastructure out of the box; for instance COM+ provides transaction, security, object pooling and some other services.

When you register a COM component under COM+ it will run "Out Of Process"; in this mode you are guaranteed to have a proxy between your COM server and its clients.

The best place I can think of for learning more about COM+ is the official MS site: http://msdn.microsoft.com/en-us/library/ms685978(VS.85).aspx

Agree with the previous post.

One thing to add: actually registering the type library (.tlb file) is normal for COM as well, not only for COM+. The type library is generated automatically by IDL compiler. It contains a description of your interfaces and objects.

So that you can "import" your COM component into some project, and the definition of the interfaces and objects are visible.