I'm a Microsoft Premier Support Partner. Their published support dates for Windows XP are:
Mainstream Support (feature requests, security updates, non-security hotfixes, complimentary support included with license, paid support): 14 April 2009
Extended Support (security updates, paid support): 8th April 2014
XP SP3 is rather like Service Pack 6a with Windows NT, in that it's a "this is the last time we're going to do this for you" service pack, but you'll still be able to get updates through the normal channels.
I think that Microsoft have understood that the corporates are not moving to Vista because it's too inefficient on the hardware. Yes, a baseline PC can be bought with 2GB ram for around £250 at the minute (in quantity), but organisations that have been organically growing or replacing hardware for the last three years are unwilling to do a complete tech refresh with new kit. My clients simply aren't interested in an OS Upgrade for the sake of an OS Upgrade, especially since it won't translate into increased productivity. I have never seen a convincing Return on Investment plan for Vista. With organisations being increasingly risk-averse, there's little that can be done to convince them that upgrading to Vista is a better option than the "do nothing" plan.
And let's be straight about this: Microsoft is a license seller. Individuals and small business really only represent the icing on the cake for them. When a company like Royal Dutch Shell refreshes its desktop estate, they will buy in one month what a national retail chain can sell in a year, and there's none of that inconvenient box-product to make & shift either. So, Microsoft don't care about you as individuals. They don't really care about Apple either, since Apple really aren't getting into the corporate space.
The only real threat to Microsoft is that corporates are continually worried that they could do better by not giving Microsoft loads of money, instead going the open-source route. As a consultant, I wonder whether Hardy Heron is ready to make the jump. Many consultants like me have Linux implementations at home, and so the consultancy firms are gaining tacit knowledge in this area, effectively free of charge. And there are compelling arguments not to put in Windows Server to do many appliance-type functions (such as file serving). Stick Samba on a blade connected to the SAN, so the wisdom goes, and forget about it. Literally. This coupled with the fact that MySQL can cover off most of the simpler corporate databases has Microsoft worried.
In the face of that, if corporates want a couple more years of support on XP, they'll get it.
