Users on LCD machines using Powerpoint under Jaguar may find bad text rendering in slideshows. I found black blotches momentarily surrounding any animated text in my presentations.
The solution is to set the Font Smoothing Style, in the General panel of System Preferences, to "Standard - Best for CRT" and Log Out and back in.
[Editor's note: I've also read that disabling "Quartz text smoothing" in PowerPoint's preferences can help...]
Mac OS X Hints
http://hints.macworld.com/article.php?story=20020915065735968