os 8.6 to 9 confusion

i'm on an imac/333 with os 8.6 and want to install os 9.
everyone says go to ebay to buy it. ok.
ebay has:
"Mac OS 9.2.1 Operating System Disk Disc Install CD"
will this do the job?
is the basic os9 software on this disc? or do i need to get that first?
please, some clarity from someone who knows.
i know this sounds familiar but i'm totally confused.
thank u in advance!

That disk would be fine. As long as it is a retail full install copy there should be no problem.
You may want to consider putting OS X on that machine though. It will handle 10.3 nicely if you make sure to max out the RAM.
If you do decide to get OS X and want to run Classic with OS X, make sure to get both CD's, one for OS 9 and the other set for OS X. Install the OS 9 first, then you can install the OS X on top of it. :black:

thank u so much!
ram is maxed and i will go to osx once i get 9 merrily installed.
have a good day

You're welcome
One thing to remember, be sure to update your iMac's firmware after you get OS 9 installed. You will need to do this before you can install OS X.
Whenever you are ready to do it, you can find it here:

http://docs.info.apple.com/article.html?artnum=75130

A good site for info on older macs is www.lowendmac.com. They have a very useful page for these models. The 333 (AKA Revision D) iMac is a good machine and well worth the time and effort. My rev D has been in daily use since I bought it (Oct 99). It has been upgraded several times: a CD-RW, bigger hard disk and a G4 466mhz CPU; and still works perfectly.

U can also check the apple forums and the apple site to learn more about the firmware update.