One of my favorites, since it is not tied into the GNOME or KDE
desktops. The program home page is located here: Wicd. When installed through Synaptic in the case of Kubuntu, it will uninstall Knetworkmanager as a requirement. Add the repository for Wicd per their site to your /etc/apt/sources.list.
Works well with (K)ubuntu, Fedora and Arch Linux. This application also
provides solid support for WEP, WPA and WPA2 (WPA1/2). And unlike
network-manager, you get to select your WPA Supplicant driver, rather
than automatically relying on WEXT.
This network manager is very fast and reliable, and IMO a much better wireless manager than Knetworkmanager. Network switching is faster in my experience. Follow the directions on the Wicd site, incl. the link on how to add a sys tray icon at startup for KDE (simple). You will like it. I learned to appreciate the functionality of Wicd while a Zenwalk user.
EDIT: I am now using Wicd in Xubuntu. Works the same way (outstanding), put the link to tray.py (systray icon) in autostarted apps per the web site instructions for Ubuntu.