OS1: Windows Me
OS2: Windows 2000
MB: Gigabyte GA-MA78GM-S2H
CPU: AMD Athlon II 160u
GPU1: 3dfx Voodoo Rush (OS1)
GPU2: Matrox P690 (OS2)
RAM: 512 MB DDR2
Sound: USB dongle + SBEMUL

The two rejects Windows Me and Voodoo Rush are working together, while on the professional side there's Windows 2000 and Matrox P690. The P690 is one of the few DX8 GPUs for PCIe, making this a DX3/DX8 build.

The motherboard has no direct support for either OS but DMA works in both (SATA SSD via an IDE adapter) and drivers for the integrated ethernet are available.

USB sound ideally guarantees minimum driver stability issues in Me. Microsoft's SBEMUL driver brings some sound to DOS games - works in Redguard, not in Screamer 2.

All components are passively cooled. One silent case fan circulates air.

There are various alternative sets of GPUs you could use. For example Radeon X series + Chinese Rage XL. The X series has better compatibility than the P690, but I already have a build with high compatibility and full MSAA for all of these games, so no real need. The P690 is more interesting in this sense, also from memory it has higher quality 16-bit dithering, though no fog. Could also do an AGP/PCI equivalent build with a suitable (more expensive) AM2 motherboard, the P650 in that case would perform about the same but have more driver options including Matrox's fragment AA.