no activeX, now what?

[JPicasso]

Okay, please forgive my ignorance, but I am still
leafing through some books trying to find the best one
to start reading.

It is my understanding that ActiveX is dead in vb.net.
So my question is: now what?

What I have is an application that needs to run on the web as well
as a stand-alone program.
What we have done in the past is to create a .dll that would take input
-from the web or a stand alone app - and return good things
in a pre-determined way.

How does one accomplish this with .net (simple explaination please)
What I need to know is what should I start looking at for an
acceptable way to do something similar.
I'm guessing webservices and XML have something to do with it?
..or am I able to do the same thing with .net, that is, code in once
place interfacing with different User interfaces?

[Magiaus]

use namespaces to order it like you would COM (this.that.dothis)and then use it on the web or on the client