7-Zip: A Great Little File Archiver

If you are looking for a free Windows file archiver that can pack/unpack 7z, ZIP, GZIP, BZIP2 and TAR and unpack (only) RAR, CAB, ISO, ARJ, LZH, CHM, Z, CPIO, RPM, DEB and NSIS, grab a copy of the Open Source...

7-Zip

It not only works well but can be integrated with the Windows Explorer so you don't even have to manually run the application to unpack files. It has become part of the standard set of tools I install on a rebuilt or freshly built Windows PC.