well for starters XP and IE are already in the minority, XP pretty much since 7 surpassed it in August 2011, and IE by Firefox in January 09 (both Firefox and Chrome easily surpass it now apparently)
The figures you have are different to the ones I have. However they still show W8 as a very minor player, so
NOT the OS you should be aiming your sites at.
Again (and this is probably my fault for not being clear) my actual point is being misunderstood. I am
NOT saying that you should
only aim your sites at XP/IE8, I am saying that you should aim your sites at
all browsers and OS (and not just Windows either, lots of people use Mac OS, Linux, etc). However XP/IE8 is the oldest, later Windows can run sites designed for XP/IE8, but the reverse is not true. And most Mac and Linux browsers were created by people aware that they would mostly be viewing sites created for XP/IE8, so can read them.
In short, design for XP/IE8 and nearly everyone will be able to visit your site. Code for later Windows and many will not, and will hate you for it. This is not a problem if your site is simply for the fun of it (eg "Bob's Amiga Fan Blog") but if it is a business site you are not only turning away customers but you are having those customers diss your company to their mates down the pub (eg "Tried to enter Walker's online competition. The ---- site would not load on my computer. If those guys can't even run a website how ---- must their ----ing crisps be?")
in business terms this is about the equivalent of telling me that HMV has gone/is going out of business because they no longer carry VHS tapes.
HMV failed to see the writing on the wall... thanks to the Internet, downloading and 'on demand' services, physical media (the lions share of HMVs business as far as i can see) has been a steadily diminishing interest.
Sorry, you have been listening to lazy tabloid journalism. This is simply not true. And if you need proof: After going bankrupt HMV was bought from the receiver by someone else. They are doing fine. And as far as I am aware the Internet has not gone away - download, on demand, etc still exists. And the "new" HMV is doing OK too. Also WH Smith's sells all the "downloadable" stuff that HMV sell, plus those book things, which are now mostly downloadable, and their main competition is the cheaper online company Amazon, but WH Smith's is still going strong.
Basically, if you hear a journalist say "They went bust because of the Internet", you are really hearing a journalist saying "I cannot be arsed to do any research, so I'll just throw in a popular myth and claim I thought of it". And if you hear a company executive saying it, they usually mean "We screwed up royally, but we cannot admit to that or no one else will hire us. Quick, we need an excuse."