I think your absolutely correct in the fact that Vista is more or less a stepping stone. Microsoft seems to release a OS , and wait for all the glitches , and bugs , to see what will and wont work, all the while receiving feedback on these symptoms. So basically , they use the end user for there experiments.
2K is still IMO, the most stable, and secure OS to date that MS has released.
Was it not Compaq, and Gateway, that mass produced systems for ME ? As Dell has been for Vista? Plus they were using Rambus , and ME had very poor memory management.
Compaq got a bad name for that , as well as them not doing much compatibility testing, do you think Dell will be punished the same?