Like some previous relies. Web Browser has became an essential part of computing experience and it would be hard to justify why Microsoft should be sued by providing an essential tool. If providing a browser should ever be sued, then Apple should be sued over providing Safari, ACD should sue apple for providing iPhoto and sue Microsoft for bundling Windows Photo Gallery. To the end, all OS that bundles plain text editor or anything called calculator should be sued as well.
I don't think Opera is making a strong argument here. Perhaps (probably likely) they could ended up having EU to get more money from Microsoft. But they have started a pretty bad demonstration on business ethic. But I wonder if they would ever care.