I don't know about KDE, but Gnome has a commanline tool, as well as an API for opening an uri with the default app. Maybe if KDE has a similar commandline tool you can use that with no memory overhead..?
In gnome the tool is called gnome-open. Also the Portland project has something going on in this area, see:
http://portland.freedesktop.org/xdg-utils-1.0/xdg-open.html
, that would be the desktop neutral way of doing things.
Infact, I just checked. In Ubuntu Edgy you can install the package "xdg-utils", and xdg-open will be available. I think it won't be long before xdg-* is installed by default on all distros to ensure portability.
Cheers,
Mikkel