dont they need a warrant to search your laptop and computer?
They would yes...in person.
That said, from a few post here and from friends, it seems that certain downloadable content *cough*TORRENTS*cough* is tracked, once it's detected, they contact the isp, shut you down, with a letter of cease and desist, stating to STOP downloading and to remove the content from your computer.
That said, it's (according to a user here...) just something in the torrent that tracks your ip adress (the risk of torrents is people can see your ip adress) and an email is auto generated...but would you take the risk?
I keep all of my files off my Laptop, that way a quick format will hide my work XD