Microsoft can’t keep supporting all the OSes that they have released so far. Even IBM will not support OS/2, Oracle will not support database version 7 and Mozilla will not support Firefox 1.. etc. IE 10 will support Windows 7. The platform preview they are releasing only for Windows 8.
There are two sets of people who are all in IE 6
(1) Pirated Windows XP those couldn’t update.
(2) Those who doesn’t know the use of Windows Update.
In both cases Microsoft can’t do much. Microsoft has already launched a website http://www.ie6countdown.com/ to help move the people off from IE 6. For Windows XP users IE 8 is the latest version available, I agree it doesn’t support HTML 5. But Microsoft doesn’t want them to stay in Windows XP for ever, Microsoft wants them to move to Windows 7 or later so that Microsoft can support the customer better & easily.
I see Windows 7 as next Windows XP after few years it will be very hard for Microsoft to kill it.
Since you own a website and have good number of visitor I urge to you post a article to do windows update (http://www.windowsupdate.com) for those users who visit your website with IE 6.
If still some users want HTML 5 in Windows XP, then I would suggest to use latest Opera browser :) (b’coz thats my other favorite browser).