I have to agree, Network Manager is a handy little applet once you get used to it. On the other hand, the Parsix network configuration utility is a peach too (works every time!!) If you want to use Network Manager in Parsix, there's a bit of a trick to installing it but should work well if you follow the instructions. Here's how:
1. Open Synaptic Package manager and search for key words "Network Manager". Once you locate it, right-click and select for installation. Synaptic should prompt you for dependency packages. Install all required packages.
2. After installation is complete and before you do anything else, open up gnome-terminal and enter the following commands as root (Note: type "su" fallowed by your root password to gain root privileges in the gnome-terminal - Parsix does not use sudo by default. Also Note: the "#" symbols below indicate the commands should be typed at a root prompt - do not add this symbol when typing the commands!)
#update-rc.d -f network-manager defaults
#update-rc.d -f network-manager-dispatcher defaults
#update-rc.d -f dhcdbd defaults
3. Reboot the computer. After rebooting, you should find that the nm-applet has started and is sitting in the system tray. If it isn't, you can start it manually by typing ALT+F2 and entering nm-applet in the run dialog box. To make it start permanently, goto System --> Preferences --> Sessions and create a new entry with the command: "nm-applet --sm-disable" (w/o quotes)
Enjoy!
P.S. A quick forum search would have revealed the above details on how to install Network Manager. Just giving you a heads up to try searching for your solution before posting.