You're missing the point entirely. No one is forcing you to upgrade to Vista or Windows 7. No one from Microsoft is putting a gun to your head preventing you from running XP or 98. They're merely saying that if you choose to buy a new machine, you're not going to be able to get an XP license on it. If you have an XP license and want to put it on the new computer, then more power to you, but Microsoft's not going to keep updating it.
My point is this: Microsoft is being absolutely no different from any other company. Does Apple let you buy a new computer with System 7 on it? No, of course not, but that doesn't mean that if you have a Mac from the 90s, they're not going to let you use it any more. Same thing with Photoshop. Adobe doesn't care if you use an old version, but if you need to buy a new copy, you'd better believe that they'll only sell you CS4.
The point is, that if companies are using software that only runs on XP, and they have machines that are used to run that software already, then they can keep it, just as they have been. The only thing Microsoft's doing is saying that new hardware comes with their new OS, and I don't see why everyone's getting their panties in a bundle over it.