No.1
Search :The Bing search is indeed a weak point but not because it's a bad product but because Google is making such a great job.
No.2
Browser : Internet Explorer.... The 9th version is actually pretty good.....The Smart Screen feature offers the best protection a user can get from any browser.Arguably their are a few downsides for IE 9, but for the average user IE 9 should be a good option.
No. 3
Mobile phones The Windows Phone is pretty new on the market...... Didn't Microsoft team up with Nokia in order to develop their phone??
No. 4
The desktop I can't agree with that , unlike the competition ( MAC OS X or the Linux builds ) Windows is a good,easy to use and reliable operating system.
No. 5
Web Server The only really problem for Windows would be on the web servers but that can be easily explained by the fact that companies love the FREE linux web server.
Microsoft it's a really big company so it's normal to have a product for each niche and lets not forget that Apple had its share of bad products