Ubuntu asking for the CD to install software

Sometimes I ask apt-get or synaptic to install something, and it asks for the CD. Turns out that this is an easily-remedied nuisance. A fosswire post (which I found by way of fsdaily) gives a GUI-based solution. An equivalent solution is to comment out the line in /etc/apt/sources.list which starts w/ 'deb cdrom:' (that's probably line 1).