
I have installed Longhorn 3683 under a Pentium 75, 64MB RAM, and a base VGA graphics adapter. You may think this is just a slow Longhorn build, but you're underestimating how slow this really is. This was an upgrade from Windows XP, and the upgrade took about 2 hours 40 minutes from start to finish. Booting up takes about 5 minutes, and the OS is extremely sluggish.
I don't know if this is due to the specs, the 640x480 16 color display, or something else, but some stuff stops working inside the build. Enabling the Sidebar does nothing, common tasks in explorer do not show up, Control Panel cannot display Category view, the My Computer folder is completely blank, and the Avalon display properties does not load and redirects back to the XP display properties dialog instead.
I also tried 32MB RAM and it hung on the welcome screen for a very long time with no hard drive activity. If anyone wants to waste a few hours of their life to try to do this on an even worse Pentium, wants to take a jab at 32MB RAM, or hell, wants to install a newer build, be my guest. I should also mention if you want to try 32MB RAM, you will need to install with 64MB and bump it down to 32 on the first boot.