Windows NT on 600MHz machine opens apps instantly. What happened?

I think a lot of that could be brought back to something closer to resembling immediacy if you go and take the time to remove all the stuff they introduced along with vista (The fadein/fadeout animations especially)

I think you mean "with XP". So bloated, with all that bevelling and shadows and DRM...

Windows 2000 was peak Windows, minus security. Security is miles and miles better today.

Nothing will change my mind about this, ever. It's been downhill since then.

Does Windows 2000 handle native Bluetooth better? What about WiFi SSID management? Does it ship with good IPv6 support?

no, no, and no. Lets see if we can petition Microsoft to add them, and then we'll see if Win2000 still runs decently fast on a P4 with 4gb of ram.

My guess is: yes, it will.

Somehow, in the past 15 years, "progress" seems to include "software keeps getting noticeably worse, but anyone pointing this out has to be shot down because progress."

Ah, there's another question, I'm running 32GB of RAM currently on this machine and 64GB at home. How well does Windows 2000 support >4GB RAM or SMP? Does it come with a good hypervisor? I do like running a lot of VMs in Hyper-V as well.

Sure sounds like there's a ton of gaps in things I really want out of my operating system on Windows 2000...