"if you look at the statistics for IE, and Windows, you see that IE6 pretty much matches up to the amount of XP users"
Where are you getting your numbers from? IE6 is at 23% here:
http://marketshare.hitslink.com/browser-market-share.aspx?qprid=2 and Windows XP is in the 60-70% range that is 2/3 of the market. Do you not see any difference between 23 % and 60%? MS has never announced IE9 won't be there for XP. It's the same reason
MS is still producing Office 2010 for XP users. The only question is whether it'll continue to use GDI which my guess would be Yes. Other browser vendors may well offer hardware accelerated rendering on XP as well using OpenGL. MS don't want to lose marketshare
and the web "battle" against Google.
You do realize that the legacy petty OS that you are bashing still as of today right now runs on 65%+ of the world's computers right? Also web developers want less different versions to develop for.
And how old XP really is doesn't matter, it is just 2 releases behind (but one of the releases was the most badly received one in the history of MS OSes and the other is a minor refresh of the one that failed). XP received a major update equivalent to a
full release in 2004, is supported with patches, dominant in the enterprise, has no issues, and remember MS released IE6 for Windows 98 as well and IE 5.5 for Windows 95.