I love the care and polish that went into the Microsoft Windows XP Welcome/Tour app that played after install. That was the peak of the summit—quality wise.
Yeah, there was a lot of good memories. And it does have a 64-bit version so not a too-bad option as a retro-OS. But I think we need to find retro hardware for it to work properly.
Actually I just installed it over the weekend in a QEMU/KVM VM on my modern desktop. Took about 20 minutes, and works very nicely. You can give it up to 4GB of RAM. Now, I can't use it for much (aside from playing the welcome tour,) because the last thing I want to do is expose it to the internet... On the other hand, I hear there is a modern browser that is maintained for it.