While generally speaking Mac OS X requires less maintenance than Windows, there are some things that can be done to improve performance and security. Below are a few things that I have found useful:
The Disk Utility, which is found in the “Utilities” folder, which is buried within the “Applications” folder can be used to verify and repair disk permissions.
OnyX – An “all-in-one system maintenance tool and optimizer” .
ClamXav – A free anti-virus for Mac OS X 10.5 or newer.
Alternative Internet Browsers for Older Macs:
Google Chrome – for Mac OS X version 10.5 (Leopard) or later.
Camino – A Firefox-based browser that can run on Mac OS X 10.4 (Tiger) or newer.
TenFourFox – A Firefox-based browser specifically designed to run on PowerPCs.
Opera – Versions 7 and newer can run on Mac OS X 10.1 (Puma) or greater .
The X Lab 
Other Options for PowerPCs:
Install a PowerPC-compatible Linux distro on your older Mac. Click here and scroll to the bottom of the page to learn more .
1. ^ OnyX Mac OS X. http://www.onyxmac.com/.
2. ^ “Opera System Requirements.” http://www.opera.com/browser/download/requirements/.
3. ^ The X Lab. http://www.thexlab.com/
4. ^ “25 Ways to Speed Up Your Mac.” http://www.maclife.com/article/feature/25_ways_speed_your_mac.
5. ^ “Speed Up Your Mac.” http://howto.wired.com/wiki/Speed_Up_Your_Mac
6. ^ “How to Install Linux.” https://renewablepcs.wordpress.com/about-linux/how-to-install-linux/.
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