PLEASANTON, Calif.,-- Jan,2005-- AdventNet, Inc., the leading provider of affordable network and systems management software for enterprises, equipment vendors, and service providers, today announced the release of ManageEngine OpManager 5.5, an enhanced version of its popular network monitoring tool for small to medium-sized enterprises. Existing customers using the 5.0 version with a valid support contract can automatically upgrade to the new version by installing the following service pack available at h......