As I recall, Windows 3.0 had an 8086/8088 mode. In the college lab I used to work in, we had 640K IBM PC systems with CGA running Windows 3.0 over a Novell Netware network. Windows 3.0 was loaded off a network drive, the PC and XT systems did not have a hard drive but a floppy boot disk to get on the Netware network. We also had bus mice on the PC and XT systems. It was I think 640x200 mode with 2 colors with the CGA driver.
Of course when DOS came out, 640K was not very common. So Windows 3.0, GEOS/GeoWorks, etc wouldn't have been possible without extra memory added.