Hey, I run Amiga OS 3.9 on my nforce2 motherboard no problem...with Amithlon of course.
And its lightning fast, taking advantage of my dual channel DDR memory @ 400MHz DDR and GeForce 3 graphics card.
Ok, I can't use the onboard soundstorm audio or the onboard 100Mbit nic, but i just use PCI cards which Amithlon supports for that.
Amiga is never going to be able to fully leverage all the current technologies the PC is using today - and the reason is ... PowerPC. Unless you are an Apple and have millions to spend designing your own motherboards, you aren't going to get that. There really isn't a market for a desktop PowerPC platform outside of the AmigaOne and Pegasos. And those companies developing those boards don't have the cash required...
The closest you will come will be the Pegasos II which will support DDR333 and gigabit ethernet. But then again, you won't be running Amiga OS 4 on it.
HammerD