It seems that the main aim of the game is to make the biggest %ge rise in the week, so the amount you start with doesn't really matter. The main flaw with the game as I see it is that the divis are ludicrously high. If they paid out far smaller amounts then there would (a) be more import attached to how shares moved in value and (b) no need for the silly capping. Anyway, they've set the rules, so it's up to us if we want to play.
Just to let you all know that I'm going away for a few days (everyone say 'ahhh'). So if this thing falls over on its arse I might not be able to fix it.