I've also just added my personal Ars Magica rules modifications it's in Word format but I'm sure you'll cope.
A bit more Ars M stuff has gone now, in particular there is the Grimoire which covers a bit more of my version of Ars Magica magic. and the Setting Material which adds more detail to the differences between my version of ArsM and canon. Finally the actual site for y ArsM game is here