SmartDraw <URL:http://www.smartdraw.com/> claims to be able to import Visio files. It can write WMF.
AFAIR, this software import preview extracted fro .vsd and convert to .wmf. That's all. [...]
Do you remember which company it was that offered translation?
The software is ConceptDraw. The conversion service is here: <URL:http://www.conceptdraw.com/en/visio/> Hub