I had Windows 2000 running on I believe a Pentium 166 (non-MMX) several years ago just for a test (64MB RAM, I think, and a 3.2GB hard drive), with Firefox 2.x, also ran Win2K (slimmed down with nLite) on my IBM ThinkPad 570 for a while with 192MB RAM and a 6GB hard drive, actually ran pretty well with Opera 11.64 and Firefox 10 ESR (although recently I went back to 95 on that machine)

I did own a 486DX/2 66 for a while, and I worked on a little project called Tiny2000 at the time (to see how small I could get Windows 2000... the target was 32MB RAM and a 1GB hard drive); unfortunately, I lost interest and I no longer own any machines pre-Pentium II... (does Windows 2000 require a 486DX? Not sure if an SX would work because it lacks an FPU... I do know however that 2000 won't work on a 386 due to 486+ instructions)

You could try in Qemu, though I seem to remember that the oldest simulated processor (on a simulate ISA machine) is the 486

Bochs surely has the 386 option:

http://sourceforge.net/p/bochs/news/

though it seems like needs to be compiled expressly for this.

jaclaz

I have W2k on a Pentium II Thinkpad 770E running on 16GB flash drive (check my post from ~2 yrs ago).  I wouldn't go lower than that.

Absolute minimum: 650 MB Hard Drive, 32 MB RAM, 133 MHZ processor (Pentium Pro+). Probably a PC designed for Windows 95, or a very high end Windows 3.1 PC would be the minimum (~1995). For light, everyday use, I wouldn't use less than 64 MB RAM, or 128 MB RAM for the Internet. But personally, I use 1 GB RAM.

http://support.microsoft.com/kb/304297/en

Edited May 12, 201412 yr by ironman14

Here is Windows 2000 running on a 25Mhz Intel 486 CPU.

 

That's an "odd" amount of RAM

36480kb = ~4.56mb... Must have some RAM on-board as socketed chips.