For those who need a refresher on Microsoft's anticompetitive actions against OS/2, go to
http://www.usdoj.gov/atr/cases/f3800/msjudgex.htmThe IBM section, starting at paragraph 115, gives the gory details.
The last section sums it up:
"132. In sum, from 1994 to 1997 Microsoft consistently pressured IBM to reduce its support for software products that competed with Microsoft's offerings, and it used its monopoly power in the market for Intel-compatible PC operating systems to punish IBM for its refusal to cooperate. Whereas, in the case of Netscape, Microsoft tried to induce a company to move its business away from offering software that could weaken the applications barrier to entry, Microsoft's primary concern with IBM was to reduce the firm's support for software products that competed directly with Microsoft's most profitable products, namely Windows and Office. That being said, it must be noted that one of the IBM products to which Microsoft objected, Notes, was like Navigator in that it exposed middleware APIs. In any event, Microsoft's interactions with Netscape, IBM, Intel, Apple, and RealNetworks all reveal Microsoft's business strategy of directing its monopoly power toward inducing other companies to abandon projects that threaten Microsoft and toward punishing those companies that resist."