content: Microsoft needed Apple.  The main reason Microsoft helped Apple was to settle a lawsuit because Video for Windows had thousands of code lines stolen from QuickTime.   Video for Windows became an issue in a lawsuit Apple filed in December 1994 against Microsoft, Intel, and the San Francisco Canyon Company, alleging theft of several thousand lines of QuickTime source code to improve the performance of Video for Windows. This lawsuit was ultimately settled in 1997, when Apple agreed to make Internet Explorer the default browser over Netscape; in exchange, Microsoft agreed to continue developing Microsoft Office and other software for Mac OS for the next 5 years, and purchase $150 million of non-voting Apple stock.  Source: Wikipedia