As I said, even the latest PCI card is unlikely to work and just not worth spending any money on. There just aren't any PCI drivers or drivers that go back to any of the PCI generation GPUs might be a better way to put it.
Again, the on-board works, just with limited resolution and no optimized driver. There actually was a 10.4.1 kext for the IEG2, but it was never updated and will not work on any higher rev.
It has been fun getting both Leo and Tigger working on the thing. I am trying to make it so it it will triple boot. Windows on Primary master, Tigger on primary Slave P1, and Leo on P2. Getting the windows boot loader and Darwin working together I may just make it. Tigger from a slave at all was a challenge. Leo was happy as slave P1, but is complaining about being P2. It may not be possible, but fun trying.
In many ways this is kind of like getting an old 3.x Novell server with jumper/dip switched interrupts and memory addresses on cards and dependent drivers back in the dark ages. You have to actually know what is in the machine to make it work. Definitely not a 1 button install.
The other thing that is weird is that even though it is a Prescott SSE3 P4, it does not like the SSE3 kernel for Tigger.