Virtual terminals are a good tool to have—they offer a last-ditch escape to command line for a chance to fix things in a crashing system. But many Linux systems come with six of them enabled, which isn’t usually necessary. You can usually disable five of them with few consequences. If you’re using Gutsy, open a terminal and type in the following commands:
sudo mv tty3 tty3.bak
sudo mv tty4 tty4.bak
… and so on, through the tty6 file. If you’re still on Feisty or other Linux distros, you’ll likely have to edit the file in /etc/inittab and add a # character in front of the lines ending with tty3, tty4 and the like.