As Microsoft faces up to another heavyweight legal tussle, this time with Sun Microsystems, the word's largest software firm will use this week's CeBIT trade show to present itself as a company willing to work responsibly with fellow IT suppliers. Steve Ballmer, Microsoft's chief executive, will deliver the keynote speech at the opening of the world's largest IT and telecommunications show on Tuesday evening. He has indicated that his address will include a declaration that Microsoft -- no stranger to allegations of anti-competitive behaviour -- must strive towards closer partnerships with its rivals. In an interview with the Financial Times, Ballmer said that Microsoft wants to be a responsible leader of the technology sector. "The industry wants us to be more responsible. We can't have business policies that are capricious or variable. We have to be reliable and consistent. We must redouble the emphasis on partnership," he said. According to Sun, Microsoft's attitude towards Java has been light on partnership. On Friday, Sun launched a private antitrust lawsuit against Microsoft on Friday seeking damages that could top $1bn (£700m), partly over the software giant's handling of Sun's Java software. "Microsoft intends to use the .Net Framework to move its current monopoly in the PC operating-system market into a more expansive and potentially more dangerous monopoly that encompasses software development on every computing device (connected to the Internet)," Sun said in its suit. The suit also seeks to force Microsoft to release the underlying source code for Internet Explorer, and to release interfaces between Windows and higher-level Microsoft software. In addition, it seeks preliminary injunctions to require Microsoft to ship Java with Windows XP and Internet Explorer. In response, Microsoft has said that this type of legal wrangling is bad for consumers.