Irrlicht Engine

What would be the best way to integrate Havok? As an animator? Or as a custom scene node?

just a small question...from where did u get the engine ?

It became free for non commercial use recently,

http://www.havok.com/

I am using SceneNodes for my IrrOdEdit plugin (for the IrrOde wrapper), but if I would re-start it I think I would be using Animators for the bodies and geoms and use scenenodes for the world and (maybe) for joints. In the way I did it the IrrEdit files get quite big because there are a lot of additional scene nodes (for the world, bodies, geoms and joints) in it.

Actually, as long as it's on PC and a game or a free app, Intel paid your license. However, if the selling cost is above 10$ and it's a game, you need to contact them for a free license so that they can evaluate that you comply with their logo rules and such. Aka:

Free app, free games, games under 10$ retail, game middleware: No need to contact them.
Games above 10$ retail: Contact for free license.
App that cost whatever: Contact for a paying license (can possibly be a non-paying one, depends of your use)

I use Havok in the form of scene node animators. That is a lot less work for integration and quite clean.

I did it like this.
http://reallibrary.juplo.com/index.html

I made a wrapper class for every trirdparty library ( Havok, Irrlicht )
and combined in one library.