Under Proportional Representation, which most of Europe uses, parties would be allocated seats according to their percentage of vote share nationwide.
Gaining 40% of the votes would hence mean the Singapore Opposition getting 34 out of the total 87 elected seats in Parliament after GE2011. The variety of parties voted in for GE2011 would then be represented with the following graph, following the percentages of vote share they gain islandwide:
Then again, if people were given chances to vote for all contesting parties islandwide, the results would most likely vary from this, even. And parties like the Workers’ Party (and even the Singapore Democratic Party) that have higher credibility and fellowship, would most likely gain an even higher percentage (40+% instead of 10+% for WP alone), something much more than the other parties, and hence allocated even more seats. Who knows, given national polling, PAP might even get less than 50% and lose the right to govern!