Karin, welcome to the forums. I would venture to say that Camtasia is probably one of the most common tools used for screen captures by users in these forums. I have recently been using Camtasia (v5) to publish my movies to the FLV format, which really work great when imported into the new Presenter '09.
This article doesn't cover FLV, but it is a good starting point for picking up the basics of integrating your Camtasia movies with Presenter. Check it out:
Using Camtasia With Articulate Presenter
If you are successful with this and want more information about using FLV let me know and I'll give you some specifics...