Well it seems a study has concluded that music sharing DOESN'T have any affect on CD sales.
Music sharing doesn't kill CD sales, study says
Here's a link to the actual study (pdf 361KB)
http://www.unc.edu/~cigar/papers/FileSharing_March2004.pdf
Here's another article on the study by The Register
Kazaa and co 'not cause of music biz woes', say Profs
EDIT: added some more links
Music sharing doesn't kill CD sales, study says
"We find that file sharing has only had a limited effect on record sales," the study's authors wrote. "While downloads occur on a vast scale, most users are likely individuals who would not have bought the album even in the absence of file sharing."
Even in the most pessimistic version of their model, they found that it would take about 5,000 downloads to displace sales of just one physical CD, the authors wrote. Despite the huge scale of downloading worldwide, that would be only a tiny contribution to the overall slide in album sales over the past several years, they said.
Here's a link to the actual study (pdf 361KB)
http://www.unc.edu/~cigar/papers/FileSharing_March2004.pdf
Here's another article on the study by The Register
Kazaa and co 'not cause of music biz woes', say Profs
EDIT: added some more links