What software do you use in your school?
With Web 2.0 and 3.0 is CD/DVD software irrelevant?
Here's what I use in my computer lab (I teach 23 classes a week of Pre-K thru 5th grade students):
Kid Pix 3D: Amazing that you can teach PhotoShop to five-year-olds and let them be creative at the same time.
Kidspiration 3: Best template program out there.  It would be enough just to have the Pattern Block Math View portion, but there is so much deeper than that.
Scratch: FREE, Open, Multi-Media, and more ...
MicroWorlds: The software of Dr. Papert.
iLife and iWorks: Keynote, iMovie, Garageband, Pages (their templates are fantastic).