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It depends on several factors, such as:

1. custom or default install.
2. HDD speed.
3. upgrade or fresh install.
4. Optical drive speed. :)

rev B, iMac G5 20" 2.0GHz and very happy with it. :D
 
When I installed Tiger on my iMac (in my sig, purchased used...included 10.3 but I wiped the drive and did a fresh install) I think it took 10-15 mins, but that was without any languages other than English and Spanish.

Edit: specs of my iMac include:

1Ghz G4
768 RAM
80gb 7200rpm hard drive
32x CD-RW
 
Generally about half an hour for me. That's including installing all my other software, configuring my preferences, and putting my files back on though. :)
 
I did an upgrade install of Tiger yesterday on my Power Mac, and it only took about 15 minutes or so. When I installed Tiger on my Power Book using a fresh install, it seems like it took around 30 minutes, but I can't remember for sure.

As an aside, people around here seem to have had trouble with upgrade installs, but the one I did yesterday worked just fine. I had some issues with the pro apps, but those were things that were very predictable based on others' experience and a reinstall of the production suite fixed them.
 
i installed tiger on my G5 a week after it came out, and it took about a hour to upgrade from panther.I dont know why it was so slow, i just told it to upgrade and leave every thing else alone.

Then about another 10-15 minutes for spotlight to index everything. I was getting a little worried as to why the all powerfull G5 was running slower than my old windows 98 system, only to find out that by clicking on the spotlight button that it was indexing files, millions of them :eek:
 
As mentioned it depends on some factors. I have done it once to do a fresh install of Panther and once to Tiger. Both didn't take very long on the installations themselves but getting my settings changed and putting all my backed up data on it took a few hours.
 
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