in the switches column of the timeline, there is a column that looks like a pixelated diagonal line icon (a quality setting). make sure that for your text layer, the setting looks like a smooth line in the opposite direction (best quality setting). if not, just click it and it will cycle throught the settings.
if that’s not the porblem, make sure opengl is off. at the bottom of the preview window on the right side there is a lightning bolt icon click that and set to adaptive resolution. you can also disable opengl all together in the preview pref, which is usually not a bad idea (i don’t think that there is a mac agp graphics card that can utilize all the opengl functions of ae, like anti-alias and motion blur)
Kevin Camp
Designer – KCPQ, KMYQ & KRCW