What can I use to unzip a .zip or .gz file?
The Windows XP machines have support for creating and extracting .zip files built into the Operating System. PowerArchiver has been installed for this purpose, look at the Programs section in the Start menu for PowerArchiver. Help is available from the Help menu once the utility is running. Under UNIX you can use the unzip command for .zip files or the gunzip command for .gz file. See the Compression/Archive section of the manuals web pages here.