I've been spending the last few days rebuilding one of my systems.
I've had a Pentium 233MMX running, with Windows 95 on it, but seeing as I feel it overlaps a bit too much with my K6-3 500 with Windows 98se, I've taken the whole thing apart.
The current configuration is K5 100MHz, a CPU I never really knew about back when it was relevant, 32MB RAM, 3GB HDD, Matrox Millennium II and a very nice Guillemot Maxi Sound 64 Home Studio.
It was really the sound card that was the main purpose of this system, as well as being a fast MS-DOS/Windows for Workgroups 3.11 system, as this sound card has the Dream SAM9407 chip, meaning it's capable of running the hardware accelerated version of Mod4win and play back modules with nearly 0 CPU load. I remember reading a review in around '96 or '97 of the Terratec EWS64, where they pointed out that I could play modules with no CPU load, and since I was into the tracker scene back then, I thought this sounded like a totally awesome feature, and it's something I've wanted to try out ever since. It's been really good fun testing it out.
WinXP : PIII 1.4GHz, 512MB RAM, 73GB SCSI HDD, Matrox Parhelia, SB Audigy 2.
Win98se : K6-3+ 500MHz, 256MB RAM, 80GB HDD, Matrox Millennium G400 MAX, Voodoo 2, SW1000XG.
DOS6.22 : Intel DX4, 64MB RAM, 1.6GB HDD, Diamond Stealth64 DRAM, GUS 1MB, SB16.