The KDE 1 task manager looks _very_ similar to the Windows NT 4 task manager (from the mid nineties): https://guidebookgallery.org/screenshots/winnt40 (scroll down to 'task manager' and click the faint tab control marked '3' in the upper left of the specific screen shot)
Until Win10, the NT OSes had that same basic task manager with the cool looking green graphs. WinNT 3.51 had a much more crude looking task manager
Thanks for the info and the tips on how to view the screenshot of the “Performance” tab. I would have been using Windows 95 or 98 back then but I don’t remember it displaying resource usage like that. I started using Red Hat Linux 6 in 1999/2000 so wouldn’t be very familiar with Windows 2000 or XP.
Until Win10, the NT OSes had that same basic task manager with the cool looking green graphs. WinNT 3.51 had a much more crude looking task manager