IMHO, I think a case could be made that a formal search warrant would be required to take the lap top and search it's content, hooked to the network or not. If the hardware is not owned by the company they have no right to search it and definately have no right to seize it. I would have to make it a huge legal issue and hire a high powered lawyer. For the hardware they own, they have all the rights and numerous cases have supported the rights of a business to do this. The other thing is that some businesses, and most government agencies retain the right to search anything in your posession if you enter their property. You supposedly abdicate your rights when you enter their property. But given that, even the military goes through a formal process to search certain containers that are considered personal property. For example, they may be able to look in your purse for security reasons to make sure you were not armed, but they would have no right to search your address book for names of people. But I am no lawyer. Someone at EPIC would know.
http://www.epic.org/