"...RiscOS computers in schools actually achieving more with their classes level of competency".
I firmly believe that to be true, from personal experience of results achieved. The reason is that the PC sets out quite deliberately to conceal from the user those underlying principles which children ought to know and which are to be taught; too many bells and whistles are actually more a distraction than useful. The Windows approach is valid in the context of the PC which is to get some sort of productivity from inexpert users in commercial offices, which is the largest user group by far (not many dollars to be got from education) notwithstanding which I've seen it stated that 5/6 of the world's data processing by volume actually takes place under one derivative or another of Unix.
And further on Sawadee says: "I find OHP good enough"
Having used both professionally,I find OHP2 with Artworks2 is infinitely more flexible than Powerpoint and indeed does a better job. Admittedly with a VARPC laptop it's useful to be able to drop out of RiscOS to show a video clip. (Tip - to dismantle a PPT presentation, copy/paste into Word and save as html. It will make directories containing all the graphics as originally inserted).