This one is for the Fusion users and maybe some of the Inventor HSM users. If you want to look at doing machine simulation for just that extra little bit of verification. Check out this site: http://cncsimulator.info/
They offer at least one free seat of the program and it is a small install.
I just downloaded it and am going to start working with it some. If anyone out there is already using it; would love to hear some feedback on it.