Tiger should run fine if it meats or beats these requirements, not especially so with Leopard/10.5...
To use Mac OS X 10.4 Tiger, your Macintosh needs:
* A PowerPC G3, G4, or G5 processor
* Built-in FireWire
* At least 256 MB of RAM (I recommend 1GB minimum)
* DVD drive (DVD-ROM), Combo (CD-RW/DVD-ROM) or SuperDrive (DVD-R) for installation
* At least 3 GB of free disk space; 4 GB if you install the XCode 2 Developer Tools (I recommend 20GB minimum)
See Tom's, (Texas Mac Man), great info on where/how to find/get Tiger...
Or Ali Brown's great info on where/how to find/get Tiger...
Will Tiger overwhelm the 1.8 GHz G5?
On the contrary, Tiger is highly optimized for the PPC processors and runs terrifically on a G5.
Tiger runs wonderfully in G4 machines with 1/3 of the processor speed, so there is no worry regarding negative processing impact in your 1.8GHz machine.
Tiger (also) most assuredly runs with more stability than Panther, and requires much lower overhead than Leopard.
Tiger is a refined OS.
I have to disagree with Grumble here. When I still had my G5 single 1.8 the upgrade from 10.3 to 10.4 and to 10.4.11 is was something I never regretted. From boot time, to everything else I used that machine for on a daily basis was faster. So not only do you get more "supported software", you get a more responsive system overall. As long as you have maxed ram I do not think you will be dissappointed.
Hope it helps!
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