apple and google are the biggest competitor of MS and if the three giant - apple, google and facebook could come together at any point to form a company then that would be the end of the MS era because the blend of the offline software technology of apple + the online services' technology of google + the mass users of facebook and it's social networking technology could make an awesome user friendly stuff!
It enterprise products - Windows Server, SQL Server, Office - are well known is the sector, and so is Microsoft's competition there with Oracle. Java ...
No one can compete to microsoft, because this company have been launching so many products which are much easier to access when compared to other products.
The worlds leading software products "Microsoft" , in Social Media "Facebook", in Search Engine "Google" then many more...!!!
If ever anybody is giving competition to Microsoft that will be Apple. Maybe Google also, but Microsoft has its roots so deep in the industry that its not going easy for any organization to uproot it and takeover the empire. Microsoft is so well known around the globe that it has no other replacement as for now. Yes, Apple is rising very fast but it will still take time to overshadow Microsoft. Most of the applications are made in compatibility with Microsoft. Microsoft did get hit by Google and Apple and others but it still rules on overall basis.
i think is Android is using only in Tablets and smart phones only, no one competitors are there to beat Microsoft.
Microsoft is boss in its own business, the same word can be told to others also, like "who can beat Google?". In near future, no one can beat them at all.
Microsoft is the best and most popular company for OS.and i believe that on one can not compete with Microsoft.