"People who illegally share music files online are also big spenders on legal music downloads, research suggests. Digital music research firm The Leading Question found that they spent four and a half times more on paid-for music downloads than average fans."
Love it. And, I know that it's true, too (I've spent a lot more on the music I want to buy since I've had a chance to check it out at my leisure before buying it in a shop / online).