The current Desktop version (1.4) does work with Windows 8. However we can not guarantee its compatibility with all systems. At this point we do not on plan on releasing an updated version specifically for Windows 8.
If you do encounter a problem, we recommend trying our web based version of WebExercises. This can be used on any operating system with any web browser. There are also many more features including the ability to add your own exercises. As a Desktop user we can offer you a free 30 day trial saving your $19.95. Please let us know if you are interested.