Those iBooks (I'm assuming you're talking about the G3 clamshells) were known to have issues and were running Mac OS 8 or 9, which were entirely different than Mac OS X, which like Linux is a UNIX operating system. Apart from the clamshells, Macs were and still are excellent computers, and Mac OS X beats Windows both in stability and ease of use.
Try Mac OS X if you can, you won't regret it.
As for Linux, you certainly can install it on your computer. Most distributions allow you to resize your hard drive to make space for Linux without destroying your Windows partition, if ever you need it for some reason.
[ January 06, 2004: Message edited by: Laukev7 ]