How hard is it for the RIAA to shut down the largest file swapping software ever? Very hard if not downright impossible. Kazaa with its 3+ million users everyday(twice the size Napster was in its heyday) was originally developed by 3 programmers from Estonia. They were commissioned to create the program from a company in the Netherlands, who later sold the rights to the software to a Vanuation company which is actually based in Australia. That spells legal mayhem for the RIAA and the record industry is losing around the world in courts. The RIAA recently lost a case in Estonia over the file sharing service and it is not looking good for the other cases currently in US courts versus Kazaa

Source: Geek News

I am also wondering can KaZaA be stopped. Because it is peer to peer, even two people can have their files shared. Therefore, I think KaZaA cannot be stopped :D