We know of two products that specialize in 3D format translation. They are:
http://www.okino.com/conv/conv.htm
and
http://www.righthemisphere.com/products/dexp/index.htm
These are both professional quality products that will produce the best results possible.
In terms of Vizard workflow, you're best bet is to get your assets into 3D Studio Max. From there, we offer a plug-in to export to Vizard that retains as much of your scene and material properties as possible.