Get Computer Info component (from LogicBase.Components.SystemUtilities.dll) is there in Workflow 8.1 RU2 but no longer exists in Workflow 8.1 RU3 and newer.
This component was removed as a part of component cleanup effort. Unfortunately, this particular component is used quite extensively is projects and slipped through the cracks when reviewing the proposed removals.
Symantec Engineering is working on rebuilding the same functionality in a component in a future Workflow version.
The component does exist in Workflow 8.1 RU2 (version 8.1.5210.0) and in a component library that has few or no ties to other libraries or components. As a workaround, older version of the library from 8.1 RU2 can be used on newer versions of Workflow Server by replacing newer version of the same library.