I'd hold off wiping your Harddrive. You may have valuable software on it.
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TenFourFox is FireFox for the PPC
"World's most advanced web browser. Finely tuned for the Power PC."
TenFourFox is noticably faster for than FireFox.
http://www.floodgap.com/software/tenfourfox/
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More RAM will help. You have the minimum. I noticed an improvement going from 768meg to 1gig.
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See what the slowdown is via Activity Monitor.
Macintosh-HD -> Applications -> Utilities -> Activity Monitor
Look at what is happening with your Mac when you run Activity Monitor.
Macintosh-HD -> Applications -> Utilities -> Activity Monitor
Click on the CPU tab on the lower half of the window to see how much time you are using and if any applications are hogging the CPU.
You can gain some understanding of Activity Monitor by looking at it every once in a while. Look at the small graph.
Here is how I have my cpu display set up:
Do you need more cpu memory.
Click on System Memory to get statistics on memory usage. You should have some free memory.
The number to look at is page outs.
Mine is 13397. This means that some of my programs and data had to be written to disk because cpu memory filled up for a time. It means my programs ran a little slower than they could have. I could run fewer programs, deal with the slowness, or buy more memory. I'd say you want at least 512meg of memory for 10.4.
If the entry for entry for Page ins/outs is:
Page ins/outs: 29163/0
Notice I have 0 pageouts which says that I am not using my harddrive for extra memory space. Thus, I have enough memory.
Activity Monitor has a neat feature where it can display a dynamic dock icon. In Activity Monitor View > Dock icon > Show cpu history.
"Reading system memory usage in Activity Monitor :"
http://docs.info.apple.com/article.html?artnum=107918
Managing Memory
See Kappy
http://discussions.apple.com/message.jspa?messageID=8025223#8025223
Problems from insufficient RAM and free hard disk space
http://thexlab.com/faqs/lackofram.html
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Here are two utilities for making a complete backup of your internal hard drive. I've recommend using one of these so that you can create a bootable system on your external hard drive. ( PPC require a firewire connected drive. ) Once created, you can run your system from the external drive. Hold down the option key on your keyboard then power on your machine. This will bring you in startup manager click on the drive image you wish to boot then click on the arrow key to the right.
"Clone, synchronize, backup. Schedule and forget it."
http://www.bombich.com/software/ccc.html
"SuperDuper is the wildly acclaimed program that makes recovery painless, because it makes creating a fully bootable backup painless."
http://www.shirt-pocket.com/SuperDuper/SuperDuperDescription.html
Has everything interface:
FireWire 800/400 + USB2, + eSATA 'Quad Interface'
&
save a little money interface:
FireWire 400 + USB 2.0
This web page lists both external harddrive types. You may need to scroll to the right to see both.
http://eshop.macsales.com/shop/firewire/1394/USB/EliteAL/eSATA_FW800_FW400_USB