WinTopo is an easy to use and very effective "one touch" vectorisation utility.  Distribution is in several forms, one of which is a non-expiring FREEWARE release.  In the image above this FREE version has been used to vectorize the bitmap to .DXF format, after which it was imported into gmax.

User input can greatly improve vectorization results.  Using the FREEWARE release the user can adjust thinning methods and polyline reduction to reduce the number of line segments used in the resulting .DXF.  This has a positive impact on successful import into other applications. WinTopo allows editing of the generated vector, to  remove unwanted line segments, prior to export.  Click on the image to access the WinTopo website.