hercufles: Also i have that I want to play the first part before playing the second or third one.
Same here. Sometimes it might not matter, but I think playing e.g. Baldur's Gate 2 or System Shock 2 without playing the first parts is just not the correct way to play them in my opinion. When Imoen comes to rescue me, it is kinda nice to know her already from the first Baldur's Gate.
But when I started playing Might & Magic 6 or Wizardry 7, I already had made up my mind that it is far too tall order to try to play all the previous games in the series.
With a game like Far Cry 2, I don't think there is any reason to play the first Far Cry before it. The games are quite different, don't share any story or characters etc. Which raises the question, why are they even marked to be of the same "series" (besides marketing reasons of course).