First, I'm definitely on battery, and not AC. Also, no, I'm not using the pm-utils to tune the parameters. I've not manually set up the pm-utils to run, and they don't appear to be setup by default in Slackware 14.
In addition, a bit more testing has disclosed some more information. If I start Fluxbox (and X11), rather than KDE (and X11), then the hard disk parameters are not changed. Thus it appears that this is a KDE thing and not an X11 thing.