The free Open Hardware Monitor software runs on Microsoft Windows with the .NET Framework version 2.0 and above. On Linux systems the Open Hardware Monitor requires Mono with WinForms.
Older version can be found in the Download Section of Open Hardware Monitor’s Google Code page.
To install just unpack the zip archive and run OpenHardwareMonitor.exe with Administrator rights. Without Administrator rights most hardware sensors are not accessible. The application is still in Beta status, so use it at your own risk.
The source code can be checked out anonymously from the Subversion repository at the Google Code homepage.
You can browse the Open Hardware Monitor source code directly online on the SVN Source Browse page.