Foes in the courtroom and applications market, Microsoft Corp. and Corel Corp. are teaming to work on the software giant's .Net platform. Microsoft last week made a $135 million investment in struggling Corel, whose CEO Michael Cowpland resigned in August. The move is interesting for Microsoft because Corel plays such an important role in the Linux community. But Corel also has been active in trying to move its Linux operating system and applications - including CorelDraw and WordPerfect - to the Web. The companies said the relationship will focus on development, testing and marketing of new products related to the .Net platform.