The trial version allows 25 accounts to be managed with no time limit. Data entered into the trial version is preserved in the registered version. Any reasonably new Windows computer will satisfy the system requirements.
If you don't have Microsoft Access on your PC, you should also download and install one of the Access runtime files below (what does runtime mean?).
This is Version 7.93. It includes the Medicare, RVG and health fund files for Dec 2015. More recent updates will be available from within the software by going to Maintenance Menu > Web Update.