Dave Richards, RealNetworks' vice president of consumer systems, when questioned by a state attorney testified that his company has been harmed by Microsoft's anticompetitive practices.
Microsoft's software licensing terms are "severe and onerous", Richards said.
Richards was put on the stand by the nine states and District of Columbia that did not settle with Microsoft to offer the point of view of a rival software vendor.
Unlike Microsoft, RealNetworks allows software developers to customise certain licensing agreements to suit their needs, he said.
Richards added that RealNetworks has been harmed by Microsoft's strict Windows licensing contracts with PC makers. For years, RealNetworks has struck deals with PC vendors to preinstall its media software as a default on the computers they deliver to end-users, but since the summer of 2000 the company has met with resistance, he said.
Hardware makers told RealNetworks they could no longer set its software as a default because of new terms in Microsoft's licensing contracts for Windows, Richards said. Windows ships with media player middleware that competes with software from RealNetworks.
This line of questioning prompted Microsoft attorney Richard Pepperman to object, claiming that the material was hearsay because Richards never actually saw the contracts between Microsoft and hardware vendors.
On Wednesday, Judge Colleen Kollar-Kotelly struck from the record more than a dozen paragraphs from Richards' written direct testimony that described Microsoft's contracts with PC makers, labelling it as hearsay.
On Thursday morning, however, the judge said she would allow the record to stand because the states attorney John Schmidtlein and the witness managed to skirt the hearsay issue.
Later she told attorneys for both parties that there are ways of restating or reframing testimony to avoid hearsay. "[Schmidtlein] was able to get what he wanted without ... any hearsay," she said, and recommended that lawyers for both parties strive to do so.
Turning his focus to the states' proposed remedies to Microsoft's anticompetitive behaviour, Schmidtlein asked Richards if the RealNetworks software that uses Microsoft's Internet Explorer Web browsing abilities would be harmed if the browser was removed from Windows.
One of the states' proposed remedies is to force Microsoft to sell a version of Windows stripped of all middleware, including the browser. Richards answered that he is supportive of the remedy and that RealNetworks' software wouldn't suffer at all.
Schmidtlein also asked if Richards was testifying in hopes of winning RealNetworks some court protection from having to compete with Microsoft on the merits of its products.
"Not at all," he answered, adding that "an effective remedy would allow us to compete (with Microsoft) on merit" by addressing the company's anticompetitive behaviour.
Another witness, Peter Ashkin, president of AOL brand products at AOL Time Warner, spoke of his dealings with Microsoft as Gateway's vice-president and chief technology officer from mid-1998 to 2000. Ashkin spent most of that time overseeing Windows licensing contract negotiations with Microsoft.
Ashkin, a witness for the states, told of how Microsoft removed Gateway from its list of approved vendors that the company purchases PCs from for internal use.
In his direct testimony, Ashkin said that in so doing, Microsoft was retaliating against Gateway's decision to use the Linux operating system on its Destination computer. When Ashkin had asked Microsoft why Gateway had been crossed off the list, he was told that Gateway was a bad partner because it had used Linux on products.
Ashkin added that Gateway believed it was not getting as good a deal on its Windows licence as other PC makers. Pepperman asked if Microsoft's proposed remedies - which also constitute the settlement agreement that the company reached with the US Department of Justice and nine other states - solve that issue by requiring Microsoft to strike uniform licensing agreements.
Ashkin agreed, but added that the states' proposed remedies go a step further by eliminating market-development agreements, under which Microsoft pays rebates to PC vendors.