They can't make all existing copies of windows media encoder disapper.

But they can change things in the latest version of windows so that the old version no longer works.
Then if you want to be using the encoder you'll have to stick with an old version of windows that prevents you from using the latest version of office etc etc.

Annoys me greatly that to run windows on my new athlon PC i have to pay for a new version because the retail win95 version doesn't run on >300Mhz AMD chips, there's a bug in the timer code, and the offical MS fix is "The problem is fixed in Win98". I've already paid them once for windows, why do i have to pay them again?