I believe V3400 we have uses the older hp plotter language for control. I have used acad 10 for doing special projects on our machine at work, but for what we generally do, it is clunkier than the software that came with the machine.
You can save to a hp plotter file, and redirect it to your parallel port. The two main problems are the machine hangs up on pen changes, and getting it to engrave where you want it to.
The bottom line is you can set up windows to print to an old hp plotter using HPGL or use a dos version of acad to control the V3400. If you want to persue this I believe I have the Instructions that the salesman gave me for doing this.
I think that New Hermes updated their software about 9 years ago. The version I have is is the DOS version update to work on win 95.