Well as I run Visual Studio.Net I'm limitied to either one of two operating systems - XP or 2k.
Ran 2k since about 2000 (coincidece?...maybe not
) and I liked it except Warlords Battlecry patch 1 didn't work and the thing took forever to boot (although I only rebooted once every 2 months but it still pissed me off). XP boots lightning fast, you can turn all the annoying visual effects off to boost performance and its really stable.
I won't upgade to XP patch 1 yet thou, coz I don't like the "Microsoft reserves the right to screw with your machine and make things not work whenever the feel like it" clause. Yep, your computer will automatically patch itself (when connected to the net) and until I find a hacking too to turn it off then I'm not upgrading.
Askan
BTW - WinMe blows. At our office we've got so sick of it we've decided to say our software not longer supports it.