SketchUp is good. I use it for my modeling.

But there is ONE thing it's bad at;

ANYTHING CURVED!

I mean sure, you can draw curves. But that's the thing, you have to DRAW them.

Organic shapes are a task not worth tackling in that program.

For stuff like that, I suggest Blender.

It's yet another free modeling program, yet Blender is INFINATELY more useful. Plug-ins for any format one could think of, capable of doing VERY good fluid animations, and very good animations in general.

The UI is scary and unwieldly at first but you get used to it.

If either of you guys need any modeling tips/help shoot me a PM.

And if either of you ever start modding TESIV:Oblivion, shoot me many many PMs!