Hidden amongst the photonovel recons for the missing episode stories on the Beeb's classic series website, there are downloadable screensavers for several Troughton stories - apparently the whole tale told in around forty telesnaps.
Visit the main photonovel menu here, and click through to the story you want. Scroll down to the bottom and you should see the link through to the screensaver.
The Power of the Daleks
The Moonbase (Cybermen)
The Macra Terror
Fury from the Deep
The screensaver is only available for PCs, running Windows 3.1, 95, 98, ME and NT.