A friend of mine asked me somedays ago who goes through if two or more teams have the same number of points in the first round of the World Cup.

Here is exactly what the Fifa Regulation book says:

Ranking in each group shall be determined as follows:
(a) greater number of points obtained in all the group matches;
If two or more teams are equal on the basis of the above criterion, their ranking
(b) greater number of points obtained in the group matches between the
(c) goal difference resulting from the group matches between the teams
(d) greater number of goals scored in the group matches between the teams
(e) goal difference in all the group matches;
(f) greater number of goals scored in all the group matches;
(g) drawing lots by the Organising Committee for the FIFA World Cup^TM.

So, the most important criterias are the games between the teams involved. On equal points between two teams that were equals in their direct match, the most important is the number of goals scored. This, hopefully, will make the teams play a more offensive style of football that will ultimately benefit all of us that watch.

Source: fifaworldcup.yahoo.com (here is the link for the regulations PDF - check page 17)