Microsoft has slit its own throat with Windows XP licensing. The number of people that i know (and i know a LOT of people who use computers) that have actually purchased Windows XP (some got it on their new computers without asking for it) I can count on my fingers and toes.
I've spent the last two days cleaning up after the bugbear virus. On Microsoft machines, of course.
Those who have made the switch to Linux don't have to worry about this. Linux is worth having *just* because it is higher quality software, and as a result MUCH, MUCH safer from a security standpoint.
Microsoft is quickly becoming an economically fascist organization: when you download the "latest" Windows Media Player (8 or above), it installs Digital Rights Management software so you can only play MP3 files which are RIAA approved...
The biggest problem with Windows and any Microsoft software is that whatever you study and learn about it is not *real* knowledge.
Learning what combinations of pull down menus to exercise to do something is superstitious behaviour... which will become obsolete next time you upgrade.
With Linux, when you learn about how programs interact with the system, that knowledge is usable to solve the next problem -- and furthermore is usable under Solaris, AIX, OS X, BSD, etc...