With his win against Henman Nalby currently has 407 points, Robredo has 410 points, Blake has 411 and Baghdatis is a bit far with 372 points.
Next week Nalby is playing in Basel, Robredo is playing in St Petersburg and Baghdatis in Lyon.
Baghdatis can start winning points just by reaching the round of 16 and Robredo will star to accumulate if he reaches quarterfinal or better. Both draws i assume are going to be moderately weak so there is a great chance for them to gain points.
Nalby on the other hand can gain points in Basel even if he loses in the first round, so a couple of good showings will improve his race ranking.
Blake will play in Paris next, according to the ATP site and he can only gain points there. But if nalby, baghdatis and Robredo all have good torunaments next week, then Blake will need to win some matches in Paris or he won't qualify.
If i made a mistake someone should point it out, but i think this is how things are right now