Is the text in a text placeholder? Are you using 2003? If so, select the
placeholder, choose Slide Show>Custom Animation. Choose Add Effect>Entrance,
and choose an effect. Then choose the effect listed in the Custom Animation
pane, and choose Effect Options. Click the Text Animation tab and choose by
1st level paragraphs, or whatever you want. That's the default, so you
usually get line-by-line animation automatically.
Ellen