Evak, you say it like Microsoft would give away new versions of Windows for free... I hope you remember that all of those desktop Windows versions did cost money and that they were released within seven years only:
Windows 95
Windows NT Workstation 4.0
Windows 95 OSR2 (only available with new PCs)
Windows 98
Windows 98 Second Edition
Windows 2000 Professional
Windows XP Home Edition
Windows XP Professional
You forgot WinME.Windows 95
Windows NT Workstation 4.0
Windows 95 OSR2 (only available with new PCs)
Windows 98
Windows 98 Second Edition
Windows 2000 Professional
Windows XP Home Edition
Windows XP Professional
Anyhow, this is slightly misleading. You're implying that Windows users have been forced to upgrade seven times in six years, when in reality this was not the case.
For example, very few people would use XP Home, then upgrade to XP Pro. A lot of Windows 95 users never bothered with Win98, while Win98 users wouldn't have paid again for Win98SE.
Personally I used Windows 95 for a long time. I upgraded to WinME because networking simply wouldn't work on Win95, then upgraded to XP Home. I have Vista on my dev PC now because I need to test my games on it.
Its called progress. You either stay with the game, or you don't. Nobody forces you.