I think that the dv5000z is the new Turion version of the existing Pentium M notebook. Note the caveat on that article stating that the disk is generally the limiting factor in notebook performance near the end of the article.
The interesting thing is that it said that DC Turion would be out in Q1 which is a lot earlier than 2nd half implies (December).
At any rate, I'm looking to buy in June and my options should be pretty good then. I'm thinking of selling the Pentium 3 notebooks well before the potential drop of support for Windows XP Home at the end of the year as I don't think that they would be able to handle Vista.
I'm going to try to install Vista CTP within the next week to get an idea of the memory footprint and performance characteristics. It will take me more time to read up on the technical stuff. It has the feel of a juggernaut the way Microsoft is probably going to jam it into users' systems.