Visio drawings can be "Saved As" either AutoCAD Drawing (*.dwg) or AutoCAD
Interchange (*.dxf) files. You need to have the drawing open in Visio and
choose Save As... from the File menu, and click on the 'Save as type' drop
down box.
Best Regards,
Aaron Rykhus, MCP, MCDST
Online Support Engineer
Microsoft Corporation