All those files you talk about are planted there by spammers and hackers and the companies that want to screw up your computer for downloading their stuff....
You need to familiarise yourself with file sizes and fake files...
These threads have some great info on that stuff...
Fake files in search results WARNING: Viruses on network you should be aware of!
Limewire is just the software that connects you to millions of computers all over the world, it does not connect you to a server and therefore it cannot control what people share.....