What other decisions does Macbeth have to make besides killing Banquo in Act 3, scene 4?

Act 3, scene 4 finds Lord and Lady Macbeth presiding over a banquet in their honor. The two murderers return to tell Macbeth that they succeeded in killing Banquo, but Fleance got away. When Macbeth returns to the banquet hall he sees Banquo's ghost sitting at the table; he begins to address the ghost, unable to hide his anguish at seeing the ghost of his friend who he murdered at the table. The company is...

Act 3, scene 4 finds Lord and Lady Macbeth presiding over a banquet in their honor. The two murderers return to tell Macbeth that they succeeded in killing Banquo, but Fleance got away. When Macbeth returns to the banquet hall he sees Banquo's ghost sitting at the table; he begins to address the ghost, unable to hide his anguish at seeing the ghost of his friend who he murdered at the table. The company is aghast at his behavior and Lady Macbeth attempts to excuse Macbeth's odd and frenetic behavior by blaming it on an illness that he's had since childhood. Macbeth finally manages to pull it together, but loses it again during the dinner. Everyone leaves and Lady Macbeth berates her husband for his behavior and for ruining the evening. 

Macbeth makes the decision at the end of the scene to send for Macduff in the morning and to visit the witches to find out how to protect himself. He worries that he might lose all that he has gained, but has come too far to turn back now.