Final answer:
The antitrust case against Microsoft for including Internet Explorer as the default web browser with its operating system.
Step-by-step explanation:
The case involving a vendor wanting to install software on his personal laptop is not mentioned in the provided information. However, the information provided discusses the antitrust case against Microsoft for including Internet Explorer as the default web browser with its operating system. The U.S. Department of Justice argued that Microsoft's inclusion of Internet Explorer constituted unfair competition to other browsers. This case focused on the dominance of Microsoft in the operating systems market and the potential anticompetitive practices used by the company.