Sebastien Biot does a good job through observational testing where KDE stands from a usability point of view in KDE Usability - First Steps.

Now that my laptop information has been migrated to my desktop I decided to install Linux on it. RedHat 7.2 with Gnome and KDE. Not much drive space after that install. Both Gnome and KDE have their own merrits, so I'm going to flip flop until I decide which one I like better. Right now I'm leaning more to KDE. It appears a bit more cluttered but it seems to have more applications to graphically control the environment. I've toiled away long enough with server's via the command line and would prefer to control everything graphically. This is also a good indicator as to how long it may be until Linux is a real alternative on the desktop. Based on first impressions, it still has a way to go.

Wired has an article on Linux being used more and more in U.S. schools due to the low cost of purchase (free) and reduced maintenance (remote volunteers). Total cost of ownership must be considered but one teacher points out that one third of his school knew Windows, the other third Mac and the remaining third were "not computer literate", so he'd have to train two thirds no matter which way he went. If anyone knows of Canadian schools doing this let me know.