Having so much time (unemployed for now) I did a test round of some of my old hardware.
Mobos:
CHAINTECH 6AIA2
PCCHIPS M825G
MSI K7T PRO2
ASROCK K7S41GX
MSI KT3 ULTRA 2 (MS-6380E)
EPOX EP-8RDA+
2x Matsonic MS8137C
ECS K7S5A
MSI K7N2 Delta 2
GIGABYTE GA-7N400 Pro2
ASUS A7V8X-X
unknown socket 370 board, with VIA KLE133 chipset
Intel Tucson i430HX, onboard Yamaha SAx sound
Intel i815 with onboard Creative 5880 (SB PCI128) sound
OEM ASUS nVidia 6100 chipset for socket AM2, made for Packard Bell
ASROCK N68C-S UCC
CPUs: Lots of socket 370, socket A, 2 socket AM2 and a socket AM3 CPUs
GPUs: All;

Results:
Intel i815 and ECS K7S5A are dead. FUBAR. So is EPOX EP-8RDA+, read that they had some BIOS chip problems so I flashed most recent BIOS by fast&dirty method (booted on a MB with similar BIOS chip, removed it and inserted another compatible chip and flashed it); no joy, is dead, Jim.
MSI K7T PRO2, one of Matsonic MS8137C, MSI K7N2 Delta 2 and GIGABYTE GA-7N400 Pro2 need re-capping.
Unknown socket 370 board, with VIA KLE133 chipset works ok even with 133 bus and a P III 1000 CPU. Downside is that OB video is slow as a snail on Xanax and has no AGP port; but very good graphic quality. Fastest PCI boards I have now are a Voodoo Banshee 16 Mb and a nVidia TNT 16 Mb.
Ones which work perfectly:
MSI KT3 ULTRA 2 (MS-6380E), CHAINTECH 6AIA2, PCCHIPS M825G, ASROCK K7S41GX, ASUS A7V8X-X, Intel Tucson i430HX with Pentium MMX 233
I was impressed by audio quality of onboard CMI AC97 codec on PCCHIPS M825G and ASROCK K7S41GX; last one even has quite fast OB video, DX9 compatible.
Working, but with some flaws:
CHAINTECH 6AIA2: OB sound (ESS ES1938 Solo) is noisy and makes noise every time I move the mouse.
ASROCK N68C-S UCC: this one has 2xDDR2 and 2xDDR3 RAM slots. Tested it only with an Athlon II x3 450; second DDR3 slot not working, but this does not bother me too much since I intend to use it as a XP rig. A 4 Gb DIMM in first DDR3 slot is enough for XP.
OEM ASUS nVidia 6100 chipset for socket AM2, made for Packard Bell: PCIex video slot not working, chipset overheating. 2x2 Gb DDR2 in dual channel.

Dead CPUs:
AMD Athlon XP 1600+ and 1800+; P III 800/100 and P III 866/133

Dead GPU:
Matrox G200 PCI

Dead RAM:
Out of 8 512 Mb DDR1 DIMMs 3 are dead. Need to buy some when I restore my financial situation (aka get a new job)

Soundcards:
Crystal CS4614: Excellent 8 Mb wavetable, but noisy, with occasional pops and clicks glitches, did not manage to make it work in DOS mode.
Terratec 128i, ESS Solo chip works great, with a NECXR385 DB (Yamaha DB60XG).
3 SB Live!, work as expected.
3 out of 4 SB PCI128 work as expected; 4th is noisy.
Yamaha XG 724/744/754: these cards are very fussy, but if you manage to configure them right they have excellent SB Pro sound in DOS and XG MIDI in Windows.
FM801: Excellent for DOS SB Pro compatibility. OKish in Windows, but for quality MIDI needs a soft synth.
Philips PSC703: Excellent in Windows, never managed to make it work in DOS even if it has DOS drivers. Sometimes sounds better than SB Live!.

Conclusion:
For now ASUS A7V8X-X with Sempron 3000+, 1 Gb RAM, Radeon 9550 and CHAINTECH 6AIA2 with Celeron 500, 256 Mb Ram, Quantum Raven AGP (Voodoo Banshee) will be mounted in a case. Also probably ASRock socket AM3.