It hasn't gotten a lot of press because of the bigger federal antitrust case, but Microsoft Corporation is also involved in a similar court case with Caldera, owners of DR-DOS. Caldera antitrust case, which alleges that Microsoft fused Windows and DOS together solely to push out DOS rival DR-DOS, was originally set to go to trial in mid January, but that date has been pushed back two weeks to February 1st.
Caldera's accusations are familiar to anyone that's following the high-profile antitrust case that was brought against Microsoft by the federal government and 19 states. However, the Caldera evidence predates anything that was brought up in the trial, as it deals with events in the 1988-1995 time frame. When DR-DOS began to grab significant marketshare, Microsoft decided to fuse Windows and DOS together so that, in the words of Microsoft's Nathan Myrhvold, "we put a bullet in the head of our would-be competitors on DOS like \[DR-DOS\], Desqview, DOS extenders, etc." Indeed, Microsoft executive Phil Barrett described the integration of DOS and Windows in Windows 95 as "stuck together with bailing wire and bubble gum."
But the parallels don't stop there: In 1989, Microsoft offered to license MS-DOS to Digital Research (who then owned DR-DOS) in return for use of DR-DOS technology in MS-DOS: This way their only serious competitor would be gone. Digital Research refused, and Microsoft began to plan the integration of DOS and Windows. Microsoft is accused of performing a similar integration with Internet Explorer and Windows when browser rival Netscape refused to exit the Windows market in 1995