Open Source file archiver Windows

If you are looking for a nice Open Source file archiver you should take a look at 7-zip.  I have installed 7-zip on a number of Windows machines and find it is compatible with more archive formats then the basic archiver that comes with Windows.
From 7-zip.org:

The main features of 7-Zip

• High compression ratio in new 7z format with LZMA compression
• Supported formats:
  
  
  • Packing / unpacking: 7z, ZIP, GZIP, BZIP2 and TAR
  • Unpacking only: ARJ, CAB, CHM, CPIO, DEB, DMG, HFS, ISO, LZH, LZMA, MSI, NSIS, RAR, RPM, UDF, WIM, XAR and Z.
  
  
  
• For ZIP and GZIP formats, 7-Zip provides a compression ratio that is 2-10 % better than the ratio provided by PKZip and WinZip
• Strong AES-256 encryption in 7z and ZIP formats
• Self-extracting capability for 7z format
• Integration with Windows Shell
• Powerful File Manager
• Powerful command line version
• Plugin for FAR Manager
• Localizations for 74 languages