I think you are (dramatically!) overstating the hardware issue. People make a big deal about mobos.... they shouldn't. As I said in the first post concentrate on the video, NIC and sound chips. Practically any current mobo that works with linux (of which there are 1000's readily available worldwide) will work. Even the devs here (sorry Thom!) overstate the hardware restrictiveness.
Video - get nVidia because it is better supported, but that is hardly a restriction. If it is a higher end device, then install the new drivers. Seriously, if you look at the instructions in the wiki it is 4 commands (that includes downloading the drivers!) and then next, next, next... Takes less than 5 mins and the instructions are perfect, I have used them many times.
NIC - just double check it is a NIC that works with Linux well and you have nothing more to do
Sound - do a search on the forums and wiki for the chip model, you will find plenty that work
But importantly, you will find loads of NICs, sound chips and video hardware that are absolutely current, so the mobo almost becomes irrelevant. The only reason I agonised over my first mobo was because I wanted a very specific video chipset, with a particular number of PCIe slots, HDMI out and various other port options and so on. When looking for such specific stuff then it can be a pain cos you will find one mobo that has this that and the other but not the right number of blahs, and another that has the right number of blahs, but not this that or the other!
You need to remember that many mobos only have a life of 3-6months before the manufacturer supercedes them, so many people's user-setups in the wiki, by definition, are with "old" hardware. But that is merely observation bias, don't let that fool you into thinking that the only hardware that works is "old". Most of the time, when they were documented they were current!
That's why focusing on mobos is not the way to go, look at the chipsets and you will find plenty of mobos that will work just fine and that are currently available in the shops....
ps. be aware that 0810 is being worked on actively by the devs, like tschak909. And that will bring in all new/updated drivers from the newer versions of the kernel (2.6.27 instead of 2.6.22) which will expand the compatibility even further so that some newer NICs and the newer nVidia chipsets will be supported out of the box.