Government witness David Farber, the director of the Distributed Computing Laboratory at the University of Pennsylvania, took the stand at the Microsoft antitrust trial today, answering questions about his 15-page written testimony. In this testimony, Farber says that Microsoft's bundling of Internet Explorer with Windows "is very likely to impose inefficiencies on application and other software developers, OEMs and retail end users." He also says that Internet Explorer can be easily removed from Windows without harming the operating system at all.

"Taken to its logical extreme, that standard would mean that Microsoft could bundle together all its existing and future applications with its current (already massive) product sold as Windows 98. Windows 98 (or whatever later version of Windows) could become the one and only universal software product, and only Microsoft could develop software for Intel-based personal computers," Farber said in his testimony.

And on Tuesday morning, Microsoft's attorneys brought out the big guns, challenging Farber's credibility as a witness and his description of what constituted an operating system.

"What business people refer to as an operating system is far broader than what you are saying is an operating system, correct?" Microsoft's attorney asked Farber Tuesday in court.

Farber said that Windows was packed with programs that had nothing to do with an operating system such as games like Solitaire. Just including these programs with Windows doesn't make them part of Windows, Farber argued.

"Your own employee calls \[Internet Explorer\] an application," Farber told the attorney. He was referring to Microsoft programmer Hadi Partovi, who had never actually made such a statement, though he did say that IE was separate from Windows.

The big debate today concerned technical issues like the system DLLs that make up the Windows operating system. Microsoft attorney Steven Holley identified 13 key system DLLs that were required by Internet Explorer, noting that removing them disabled Windows completely. Farber wasn't impressed by this news, saying that the 13 DLLs were standard system DLLs that are not part of the Web browser. Internet Explorer, he said, was purposefully "welded into the box."

"Other than a very high level of generality, you do not know anything about the internal workings of Windows 95 or Windows 98, do you?" Holley asked.

"No," admitted Farber, whose cross-examination will continue tomorrow