i used vista for almost all of last week and formatted back to XP becuase I couldnt' work with it. It took 2 hours to import only 200 images into Adobe Lightroom (god knows how long it would take for All of my images), it takes about 20 minutes on XP. Once i got them imported, I couldn't do anything becuase it was so slow. I also couldn't get Photoshop to work on vista so that just made it worse.
I went back to XP becuase I couldn't work on what I needed to get done.
EDIT: And vista asking permission to run every program is a joke.