Files ending in .zoo normally signify files which have been bundled and compressed using the zoo format. Utilities supporting this format exist on a wide variety of operating systems, including UNIX, MS-DOS and Macintosh. Files ending in .zip normally signify files which have been compressed using the ZIP format, which is available on a wide range of systems, and is the most popular compressed file format for PCs. There are in fact two ZIP file formats, the original and version 2. The latest version of the 'unzipper' program should handle both types with ease.
Most archive sites provide the necessary 'unzipper' as an auto extracting file.
The two popular ZIP archivers are PKware's PKunzip and Infozip unzip. PKware's offering is shareware and is also available from Computing Service Sales. Infozip is freeware. Once converted to a binary file you then have to unzip the resulting file. PC arc files Files ending in .arc normally signify files which have been both bundled and compressed using the arc format.