Leo Notenboom has a very interesting article on the end of support for the various Windows operating systems.
XP, he says, has been supported for 12 years when the normal lifespan for any OS, including Linux, is about 5.
After that, it gets too expensive to maintain.
"Mainstream support for Windows Vista with service pack 2 installed ended two years ago
on April 10, 2012. Extended support, in other words security fixes only, will last for another three years ending on April 11, 2017.
"Windows 7 with SP 1 installed comes to its mainstream end of support date next year: January 13, 2015. The end of extended support is January 14, 2020.
"And Windows 8, - actually Windows 8.1 – will have mainstream support until January 9, 2018 and extended support all the way into 2023."
How does mainstream support differ from extended support?
Read about it here.