To remedy the situation, I discovered another graphical network manager called WICD. The version in the Ubuntu repositories was actually a bit buggy, so I went directly to the WICD launchpad website and downloaded the latest release (version 1.7.0). I've tested it out at home and away and I can now say that it works quite nicely. WICD allows Ubuntu to start up my wireless connection before the Login screen. It also allows me to connect to other wireless networks despite the settings in my /etc/network/interfaces file.
As you can see above, WICD puts an icon in your system tray with a green indicator bar that tells you how good your signal is. If you hover your mouse over the icon it tells you what network you're connected to, what percentage signal strength you have, and what your IP address is.
Above is the window that pops up when you left click on the WICD icon in the system tray. As you can see, the window contains information about all available wireless network SSIDs in your vicinity, how strong the signal is to those networks, and what type of encryption (if any) protects each network. You can click on the properties button for any network that you want to connect to if you have to put in a wireless encryption key. The screen that pops up follows
Once you're ready, you can click on the Connect button and you're on your way!
Setting Up WICD
As I mentioned above, I first installed WICD from the Ubuntu Repositories. I think this forced my computer to install all the appropriate dependencies so that the newer version could work. When you download the newer version, extract it to whatever directory you want. Then, open up your terminal, navigate to the directory with the WICD setup files that you just extracted, and type in sudo python setup.py install. Now, when you restart your computer, you should see WICD in your system tray ready to do your bidding.