Microsoft Office 2008 for Mac was designed to run on both PowerPC (PPC) and Intel processors. It supports the following operating systems:

Your old Mac may still have life in it, but you must use the software designed for its era. Trying to force a Windows version number onto a Mac operating system will only result in frustration and potential data loss. Stick to Office 2008 for older systems or LibreOffice for El Capitan, and you will be editing documents smoothly within the hour.

El Capitan is much more modern. It runs on 64-bit Intel Macs.

You need to write a thesis, but there’s a problem: the world is moving to the ".docx" era. The Quest for the Installer

What is the you need to complete (e.g., opening a specific file, basic word processing)?

Very "light" on system resources; highly compatible with Tiger.

Tiger is difficult. Most modern software refuses to run. Your options are:

If you cannot find a retail copy of Microsoft Office, these open-source suites are excellent free "downloads." Specifically tuned for Mac OS X.