How to install-- It's easy :
1. First, click a link above. You should see a "Save File" option. Click it and wait for the file to download.
2. Once downloaded, you should see an "Open File" or "Run" option or see the setup file icon in your browser's download menu. Select "Save", "Open File", "Run" or double click the setup file icon,and go through the installation process prompts. It's easy.
NOTE: If you get a "corrupted" download when using the Internet Explorer browser, the Arithmemouse setup file is fine here; it is just the Internet Explorer browser downloading incorrectly. You need to either use a different (ahem..."better") free browser to download with like Chrome or Firefox, or within IE go to Tools>Internet Options>Browsing History>Delete [select Delete]. Then download again until IE gets it right. The issue is explained here. Confound you Microsoft! ;)
(Click this support link for more help downloading.)