So the more easy is podium http://www.suplugins.com (only 2 cursors) and cheap (179$) or free in 500*500 without logo or watermark but it's a plugin of the free Google Sketchup ;)
No problem as Moi has the Skp native format :)

A little less easy is TwillightRender and super cheap (99 $) http://www.twilightrender.com/ or free in
* 800 x 600 pixel maximum resolution
* Rendered image watermarks
* Images only savable as JPG
* XML export is disabled

LightUp 149 $ http://www.light-up.co.uk/ Real time render after one computation of the scene
Interest of this 3 programs is that you control all objects inside Google Sketchup the more easy modeler!
http://sketchup.google.com/intl/en/
And you have the biggest free objects library at http://sketchup.google.com/3dwarehouse/

And you have an another solution and free ;)

A new world of simulations in real time: export on any supports, computers, Web, console etc...
http://unity3d.com/ (free as Indy name section)

Have happy rendering!

Here Podium in free version 500*500 with a Moi Object : you see the interface with the 2 cursors
Small is beautiful ;)