it eats up tons of resources, it won't even install for many people for absolutely stupid reasons (it wouldn't install on my other PC cause my videocard is not compatible with my MB.. if it wasn't, why the fuck were they running fine for 2 years together?), and it commits suicide rather regulary, not to mention that it is incompatible with ALOT of older drivers/hardware.
I run winxp: WinXP Uptime: 2wks 5days 7hrs 50mins 28secs
It doesnt crash that much, and the compatability is better than 2k. It does have install problems for lots of people though, and it doesnt eat that much more resources than 2k. If you have the machine for it, I recommend xp.
With Win3.x, the feared words weren't "(color) Screen of Death), but rather "General Protection Fault". All it takes is one badly-coded app, and the system comes grinding to a halt (not entirely unlike MacOS).