Reasons to stick with VectorWorks:
1) Price: VectorWorks is half the price of AutoCAD
2) VectorWorks can produce Spreadsheets, cutsheets, material estimates, material lists, integrated 3D rendering (w/ RenderWords), scriptable, and superior Import/Export options
3) AutoCAD is NOT Mac compatible!
4) If your company did decide to switch to Autocad they can expect to pay for each new Windows based machine in addition to each AutoCAD program or site license in the office. (that pretty much kills your bottom line as a company... profit)
5) In addition to the new computers, your company may as well hire a new IT division to handle all the problems that are associated with Windows based machines. Apple computers are more stable... particularly the new G4 and G5's.
6) AutoCAD isn't terribly stable.
I hope that helps a little.