WinRar

You have probably come across the file type .rar when downloading larger files or installation packages. The RAR format is used to compress large files, say a movie (700mb) into many smaller files (45 files x 15mb). When you download something and it is in RAR format (a group of smaller files) you have to extract these files to recreate the single large file. A great program to achieve this is WinRar. WinRar will let you extract rar files as well as let you make your own out of any large file. WinRar is a pay product but the trial version comes complete with all the features you will need and does not run out. Check out the WinRar site and download the trial version from here. Select the grapgic and command line download. Once installed simply navigate to where that pesky set of rar files you just downloaded is, right click on one of the files and choose "Extract Here". Winrar is also great for use with zip files and iso's.