Note that you can also tweak a few parameters of the physics engine. For example, you can reduce the stepSize of the physics engine to simulate in temporal steps that are smaller than the refresh rate.
See the last section here, "Tweaking."
http://docs.worldviz.com/vizard/Viza...ics_basics.htm
Under the hood, Vizard is running the "ODE" physics engine. If you wanted to, you could import your own physics engine, but it's a bit of work. I've done it. If you don't need something that is close to an idealized physical model, ODE should be sufficient.
Note that ODE's calculation of bounce dynamics can be more accurate than Vizard allows, but there are a few parameters of ODE that Vizard doesn't give you access to. This is a separate issue than collision detection.