Installing internal hard drive on an old iMac

Question

I am an absolute novice when it comes to taking apart a computer and know nothing about any technical terms or parts. I was able to install a new battery when the original died, so when the "genius" at the Apple Store said I could install an additional internal hard drive, I gave it a whirl. Before I try to return the hard drive, I thought I would give this a shot.
My iMac is a 400 MHz PowerPC G3, one of the early generations, if the not the first (see-through cobalt blue exterier). I am running with 256 MB of memory and the CPU type is PowerPC 750 (83.0). I have Mac OS X Tiger, version 10.4.6 and this machine had been working great until we recently purchased our first iPod. Now with all the music being loaded in iTunes, the iMac has slowed down and even frozen when trying to use a few applications at once.
I figured I needed more hard drive space and/or memory and the people at the Apple store suggested I purchase a Seagate 80 GB Barracuda and install it myself.
Well, I got the computer apart and found the old hard drive, but that is about as far as I can go. I read about making the new hard drive the "slave" hooking up the BLUE, BLACK and GRAY connectors on the new cable, but I don't know a motherboard from a jumpdrive and the new connectors do not match up with the old one (the Blue connector is not the same size as the old one that I think was going into the motherboard). There is also something about an unused power cable in the old computer for the new hard drive, (which I did not see) and a suggestion that I get a Y-shaped power cable from an electronics store, which even if I knew what it was, I would not know where to begin connecting it. Not only does the new connector not match up, it is about 10 times as long as the old one, which leads me to the final issue: if I could get this all hooked up and power-supplied, where in the world would I put the new, additional hard drive? There is no room I can see adjacent to the current hard drive. Do I have to take the thing further apart?
I realize this may provide a great laugh for anyone who knows how all this works. If trying to walk someone through this process using Apple Discussions does not make sense, I completely understand. I had nothing to lose (except possibly the cost of the Seagate drive if they won't take it back).
I was able to put everything back together after taking the old hard drive out, so I think I could do this if the parts were all there and matched up....but I would still need to know where to put the new drive!
Any suggestions are appreciated. I have already resigned myself to the fact I may just need a more expensive external drive...I just have few available ports.
Thanks,
Conrad Farner

Answer 1

"...when the "genius" at the Apple Store said I could install an additional internal hard drive, I gave it a whirl... if I could get this all hooked up and power-supplied, where in the world would I put the new, additional hard drive?"
Your iMac has room for one hard drive and the optical drive (CD-ROM, DVD-ROM, CD-RW, etc.). Any ribbon cable supplied with the hard drive or a Y-splitter power cable is of no use in the iMac. The new drive must replace the original, because the two can't coexist internally. Additionally, you need to configure the new Seagate as "master," since the optical drive is "slave." Refer to Seagate's accompanying documentation, for instructions on setting the small jumper(s) to designate the drive as "master." The drive may have been factory-configured for "cable select," which isn't supported in your iMac. After you get that straightened out, you'll need to boot the computer from the Tiger installer CD and use "Disk Utility" to format the new drive as a Mac OS Extended (HFS+) volume. You may also want to partition it as well.
Incidentally, you should post any future questions about your iMac in the Forum dedicated to the CRT-style iMacs. You'll receive informative answers to any questions that you might have, from those who are thoroughly familiar with your model iMac.