I have an Advent laptop, but when the speakers are turned up to any volume, I hear noises that can only be described as the computer doing stuff.

E.g, they emit a tone when I move the mouse or they exaggerate the sound of my DVD drive. How can I stop this?

Enough said with the Advent really!

They're notoriously bad at insulating the sound card! You need either a seperate sound card (ie PCI or USB) to solve the problem.