The industry really wants you to get Windows 8 via an all-new PC, and most people who adopt it will go that route. But, if you don’t, or can’t, and have even a three-year-old PC, you may want to just stick with the Windows you’ve got.
It looks like Microsoft (with the eager cooperation of the OEMs) is back up to its old tricks. It used to be routine to have to upgrade your computer to use the newest Windows, but Vista was such a resource hog that MS had to make Windows 7 leaner to appease angry consumers. It looks like the industry is secure enough in Windows dominance of the OS market to put everybody back on the treadmill again.