I guess it's just an opinion thing, but I don't think 2000 was that much above NT. When looking back on 2000, it's interesting to see those who like it complain about Vista's stability and polish. 2000 was unusable until SP1, and not really stable until SP2.
True, but that's expected with MS operating systems. For the servers I maintain, 2000 has been night-and-day better than NT 4. We didn't deploy 2000 until SP2 was out. We're just now rolling out Server 2003 in a major way, since SP2 has been released.