Upgrading Hard Drive in iMac G5?

Hi Community -

I've got my hands on two new products that were being thrown away, a dual 2.0 GHz PowerMac G5 with 5GB of RAM, and an iMac G5 single 1.6GHz with 2GB of RAM.

This topic concerns the iMac, I am planning to upgrade the hard drive from the standard 80GB 5400RPM to a 2TB 7200 RPM hard disk pulled from a new Xeon Mac Pro. However, I install the hard drive correctly, (I'm experienced in hardware and such) and I boot into the Tiger install, and it isn't listed in Disk Utility, or as an available option to install Tiger to, only the disc drive is listed.

I went ahead and tried another 320GB 7200 RPM disk drive, and I have the same problem. So, I tried reinstalling the original small 80GB hard drive and it boots just fine, and comes up in the installation disc.

What is the problem of this? Does the Tiger installation disc not support 2TB? Also, why wouldn't it support the 320GB either?

All help is much appreciated,

-Nick