.rar is like .zip you need WinRar to uncompress the file as for what to do with the contents Im not sure as I don't know what is inside them and it very well could be a virus so goodluck with that
You can get Winrar from here: http://www.win-rar.com/
As Blues said, Once extracted it might be worth running a good virus scanner over it such as AVG Free. Then it all depends on what file format is inside it. It could be a bunch of files which make up the CD, it could be a .iso file, a .bin etc..