you happen the know how well if at all Ubuntu 10.04 PPC wil run on a eMac and use the AirPort AND bluetooth?
Yes, I have an eMac here that I have Ubuntu installed, in addition to OS X 10.5.8
I have Ubuntu 11.04, which works fine. There is then an upgrade to 11.10, or even to the next 12.04 Unbuntu. I cannot get either to boot on the eMac.
I think that the best Ubuntu for your eMac is version 10.10
There are extra drivers for the Airport card, which works fine in Ubuntu.
Ubuntu installs bluetooth drivers, but I don't have bluetooth devices, and don't know if bluetooth works in Ubuntu.
Yes, you can upgrade directly from 10.3 to 10.5
You absolutely should NOT use the default Upgrade option from the 10.5 installer. You must choose the option to Archive & Install OS X. You'll see that simply by clicking on the Options button.
How much RAM memory in your eMac? 10.5 needs at least 512MB, and 1GB is better. 2GB is best, if you have an eMac that uses PC2700 RAM.
I think we can choose to disagree on Snow Leopard. I don't see much difference between Leopard, and Snow Leopard - except for much better performance. All it needs is lots of RAM.
It's not possible to use Snow Leopard on your eMac, so that's a moot point...
If you mean the current Lion (10.7), then I can definitely see your point of view. Lion is substantially different, and many Mac users find it difficult to get used to, for a variety of reasons. (but, using it for a while - I really like it a lot! I could go into the reasons, if you have any interest)
And, the 10.5 installer will install on either your PowerPC eMac, or any intel Mac that's more than 2 years old. The core2duo processors are so much faster than the G4 or G5, there's no contest. SO - you can have a much faster Mac, and still stay with 10.5 if you want to do that.