If you want zip and unzip, you do not have to install another explorer. All you need is WindowsMobileZip Explorer Extension. It is a Zip-Unzip plug in for the Windows Mobile 2003 file explorer.
WindowsMobileZip Explorer Extension makes it easy for you to compress and uncompress file or folder directly from your Windows Mobile 2003 file explorer: simply tap an hold on any file, the context menu will pop up with additional menu to zip or unzip a file. It is simple, easy and elegant. The Trial version is a full running version with the exception of the additional about us command in the context menu and regular about us pop up on any add on command.
Caution: this software requires Windows Mobile (Pocket PC) 2003.