Windows is the name of an operating system produced by Microsoft. Microsoft used to sell a superior operating system named NT then Microsoft infected NT with a virus named Internet Explorer, making NT as unreliable as Windows. Microsoft then transferred a few bits of NT into Windows and tried to pass Windows off as the replacement for NT. If you want NT reliability and stability, switch to Unix.
Windows used to be preinstalled on 99 percent of all computers. Now the percentage is down to 90 percent and falling fast. Microsoft is no longer allowed to force computer manufacturers to install Windows on all computers if they want Windows on just some computers.
People used to install Windows just to run Microsoft Word or Excel. You can run both programs in Linux using Wine. OpenOffice does a good job of editing Microsoft Word and Excel files in any operating system without Microsft Word or Excel. I have several licenses for Microsoft Office and do not use any of them because it is easier to use Abiword for my own word processing or OpenOffice for documents sent to me by Microsoft Office users.
Microsoft Outlook was a popular choice for email but Thunderbird does everything you need and can run anywhere. Microsoft also sell Outlook Express which is totally unrelated to Outlook and is the cause of more support calls than anything else produced by Microsoft. The only cure for Outlook Express is an upgrade to Outlook or Thunderbird. You can convert from Outlook Express to Outlook but then you have to convert from Outlook to Thunderbird to make your email secure.
There really are few reasons to use any version of Windows. I use a few applications that run in Windows but I do not use them very often. At one stage I used 60 applications on a daily basis and converted 30 to replacement applications that work on both Windows and Linux. Gradually the percentage of Windows only applications withered down to a skinny bunch I could probably throw out.
Ubuntu is the best replacement from the Linux family. Linux lacked a replacement for NTFS then gained the almost as good ext3 file system. Linux lacks the flexibility of the Windows security system, something that is not relevant to single user desktop computers. Much of the Linux documentation and support forums still lurk in the dark ages of 1980s command lines but there are people producing readable usable pages.