It's funny to see that you list DOSBox seperately from the emulators. (as it is an emulator)
Anyway. I got a second hand laptop a few years ago
It's pentium I 100 Mhz with 64 mb ram
It runs win98 and debian linux with a self written Xinit script (no window manager) resulting is blazing fast system without any fancy stuff
It's been a while since I used it. But I use for it programming mainly.