Various iMac problems: reboot and upgrade

Question

Please help:
My school unearthed a old iMac, and intends on loading it with a language software, and it fell to me to make it work. From the files I could find ( I am not very familiar with the OS it was running, the only Mac I use is OSX) _it is from 2003-ish, and is running OS 9_. Here are the problems with which I need your help.
1. It is S L O W . It took 15 minutes to bring up the hard drive and look at the file headers on it. Dragging anything to the trash freezes everything (including the clock) for about 1-2 minutes. Any good way of fixing this? Will rebooting the hard drive to factory settings work? *How would I do that?*
2. The software the school ordered needs OS X. What is the (cheapest) and best way to upgrade, and which version should I look for?
Thank you very much for your help,
~ Anonymous Intern

Answer 1

You can find out lots of information in Mac OS 9 System Profiler:
Apple > Apple System Profiler
Click on the System tab
Look in the Memory Overview & Machine speed. The machine speed will give us the exact iMac model.
Checking the firmware.
Figuring out what level of firmware you have.
1) Mac OS 9.x or 8.x, you need to use the Apple System Profiler.
Apple -> Apple System Profiler
2) Open Firmware, boot into Open Firmware.
Power on your iMac while holding down commandoption+of
The first output line contains the firmware level. Mine reads:
Apple PowerMac4,1 4.1.9f1 BootRom built on 09/14/01 at 13.18.04
Copyright 1994-2001 Apple Computer Inc.
On my machine, I have 4.1.9f1.
What firmware do you need?
http://docs.info.apple.com/article.html?artnum=86117
Also, why would I replace a battery? It works fine, and is a desktop, so it has a power chord.
Some of the iMac machines do not boot without a working battery, and you get the wrong time. If you have the machine open, you might as well replace it.
You can replace the batter by going through the memory slot. It's tricky.
Robert