7zip is a FREE software (free as in freedom as well as free beer) which you can use to deal with a variety of compressed formats. It is lighter compared to other compression utilities like Winzip or Winrar.
7zip is licensed with a LGPL, meaning you can make as many number of copies of it, redistribute it, sell it, acquire the source code, modify it and sell/distribute the modified copies.
7zip also allows you to compress into .7z archive files which has a very high compression ratio coupled with higher compressing and decompressing speeds and AES-256 Bit encryption methods.
It can handle file sizes upto 16000000000 GB!!!!!!!!!!!!!!!
Being a Free and Open source software the development speed and bug corrections will be much faster compared to proprietary softwares like Winrar or Winzip.
Download 7zip from http://www.7-zip.org/download.html
You can download 7zip from http://www.7-zip.org/ (it is just some 857 KB download)