If you leave your machine running all the time, the system performs a number of routines for you. Usually in the small hours of the morning.
Yasu is a nice disk utility that does a bunch of stuff and also uses the built in Unix routines. There are a number of good disk utilities out there. Check the OS X software tab under the Apple Menu.
Disk Warrior is also a must have for every Mac owner, <9 or X, along with TechTool Pro.
Defrag is something that you can do but each time a program is installed, the system does a little defrag, optimizing the system, at the end of the install.
Repairing Permissions is also good to do before and after each large install, or about once a week if you are not the avid installer.
Hope this helps
P
I don't miss ...
all the adware/virus searches, hd defrag/registry reviews not to mention the added cost of software needed to keep my old winbox running...BUT...
Is there any regular maintenence routine that Panther (what I have) or Tiger requires to keep my system running smoothly ?
Thanks
Grim

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