Windows XP: due for sale on 25 October
Daum Communications said it has filed a complaint with the Seoul District Court to block the sale of Windows XP, arguing that it will stifle its own internet messaging product.
Windows XP is due for a global launch on October 25, in time for the Christmas sales season.
The new software revamps Microsoft's windows operating system, and is set to become the firm's bridgehead for its new net-based services.
Innovation and privacy
By bundling so many features into Windows XP, Microsoft will "strip domestic consumers of their chance to select the services they want" and amounts to an unfair business practice, said Daum.
The court filing from Daum, which has 20% of South Korea's market for instant messaging, highlighted Microsoft's decision to package a similar service as part of Windows XP.
Consumers privacy could also be breached by the amount of information Microsoft demands during installation of the software, Daum added.
Bill Gates visit
Daum said it is part of an alliance of 18 companies, who will meet early next week to discuss their next step.
Microsoft chairman Bill Gates is due to visit South Korea on October 16 on his way to the meeting of the Asia-Pacific Economic Co-operation (APEC) body in Shanghai.
The development of Windows XP has been rocked by a series of controversial components as well as the ongoing antitrust trial with the US government.
The court filing is Daum's second action against Windows XP. It filed a complaint to the Korea Fair Trade Commission (FTC) in September 2001.
Microsoft said it is witholding comment until either the commission or the court responds, though it would be willing to talk to Daum.
"We don't feel the need to officially respond unless the court or the FTC makes a decision", a Microsoft spokeswoman said.