You need a firewire port only to meet the system requirements for OSX 10.4 Tiger.
http://support.apple.com/kb/ht1514
No physical need for the installation itself.
Here are the system requirements for OSX 10.3 Panther
http://support.apple.com/kb/HT2176
The original iBook came with Mac OS 8.6, the faster models with OS9.
So you have to look for black retail CD/DVD for installing OSX 10.3 or 10.4
The grey ones were bundled with other models and will not work with your iBook.
For a start, you may try the free linux distribution Ubuntu 5 to see if your ibook is working.
http://old-releases.ubuntu.com/releases/5.04/
Download the PowerPC Live CD iso image. Burn the ISO by using your windows PC and put it in the optical drive of your iBook.
After pressing the power Button push the ALT key and a screen with the bootable drives will appear. OSX will show up and your Linux CD. Choose Linux and you will be guided through the next steps.
Live CD means that you can try out the system prior to a real installation (without writing data to the disc).
A maxed out iBook with 576MB RAM and a bigger HD >20GB can run Ubuntu 10.