http://tennislive.free.fr/ Fed can gain only 500 points if he WINS MC while Nadal can gain 1000 even though he is the defending champion... im so confused right now

It's to do with the fact that Monte Carlo is not a mandatory event and Roger having 3 0 pointers in his 500 events count. If Roger wins it will replace his Basel 500 points, raising his total points by 500.

MC counts as a 500 tournament in the rankings system as it is non-mandatory. Fed already has 3 zero-pointers in his ranking for lack of 500 tournaments played. The first of these is Hamburg in July, so Fed's full Monte Carlo points aren't counted until that zero is dropped. If he makes the final he gets either 600 or 1000 points, which will replace his 500 points from Basel as his 4th 500 tournament.. hence 500 max points here. The Basel points would go back on after Hamburg though.

I think this is only true if you're carrying a lot of 500 zero pointers i.e. if MC is your only countable '500' then it is counted in the 500 column - if you see what I mean. Rafa's and Murray's ranking breakdowns both have MC counted unders masters 1000 events.

It's called Project Points (This is the Players New Points Total for NEXT Week after taking off the 2010 points and adding the score he has earned at the time)