I still use it on a "guinea pig" machine I have. Throw on the free ZA firewall (if you don't have a router), add msconfig functionality, and you're good to go!
It's ridiculously stable. Love it. I think a lot of people, myself included, have sort of a sentimental attachment to it 'cuz it was the first OS that didn't suck , and computers could actually be fun and useful without all the frustrations associated with Win95 and 98. "This program has performed an illegal operation and will be shut down :evil:" -- you guys remember those? Dang, I hated those messages!
Sadly, W2K's days are numbered because more & more software now will only run on XP and Vista. I just bought Acronis True Image 2009, and it won't run on anything pre-XP. Oh well, nothing lasts forever.
Five-seven years from now there'll be threads titled "Is anyone still using Vista"?