I'd highly recommend Tyan. I use them for Socket F Opterons but from your CPU speed, it looks like you've got 800 series (socket 940), not 8000 (socket F). Please correct me if I'm wrong.
As of right now, I'm unaware if Tyan has any Socket 940 motherboards available and if they do, they certainly aren't actively listing any on their website, but they list a whole slew of 940 motherboards in their archives.
Some people may recommend Supermicro and I've used them nearly a decade ago, but I've always seen Supermicro lean towards the Intel camp and at times it seems like AMD is treated as a stepchild in their product line. Just my opinion of course. ASUS and Gigabyte may be vendors to investigate, but as companies go, their market is in the enthusiast sector - not typically workstation/server sector.
You might be able to snag a good deal on eBay and such, but a little more information is needed as some of these motherboards may only fit eATX (full tower) vs. ATX (mid tower). The price and size differential between eATX and ATX can be large. I've built several Tyan Opteron server systems and in terms of quality, they're great but in your specific issue, case size may determine the motherboard you can buy.
On a side note: another factor for your home is heat and noise. You may want to investigate cooling and noise issues as if these systems will be in your home, take that into account. I'm currently looking into water cooling my dual socket F rig as noise and especially heat are becoming serious issues.