General Maintenance for G5?

My apologies if I could have gotten answers elsewhere...

I got a G5 during January (Having previously been a Windows-Only person), and I've finally decided that I need to know what sort of stuff I should be doing to keep it running well and whatnot. I'm pretty much still a newbie, and I don't really know what the majority of the Utility programs do, which ones I should use regularly, and how often I should use them.

If somebody can give me some information on general maintenance for my Mac, I'd appreciate it.

After any system updates, installing programs and once a month usually

1) Repair Disk Permissions - Go to Applications|Utilities|Disk Utility and select repair disk permissions on your OS X drive

do a search for "crons" and you will find a bunch on running crons (I don't do them that often so forget the whole story behind them)

Wait, "crons"?

there is a thread dedicated to utilities
here

i suggest Macaroni.....9 dollars (U.S.) and you never have to worry about maintenance again!

I won't fill up the forums with another post so I'll just use this one. My question is about my poor sick G5. I went on vacation 2 weeks ago and when I got back, my G5 started acting strangely. The fan is now constantly running and it's quite loud. The fan used to run for the most part only when a CD was in the drive, but now the fan runs from the time the computer is turned on until it is shut off. Any help with this would be much appreciated. Thanks.

I suggest running OnyX every month and after major software updates. Free program.

I downloaded that but I get an error that says no such file or directory, then it opens the application and asks for my administrator's password which I give (assuming it's the OS X admin they're talking about) and it says the password is either invalid or missing a ! So I don't know what's wrong with that either. This is quite a mess.