512 MB RAM is the maximum RAM of the clamshell iBooks, and 500 MHz+ is required for MS Office 2008 .
Tiger can run MS Office 2008, though. Hopefully, I'll get the school to stop using .docx and switch to the Open Document Format ... Plenty of students I know can't afford Word.
The TiBook needs to run some bloated web-apps, as well.
My old middle school required office 08' but they then switched back to 04