If you are afraid of them finding and searching your files, your ONLY way to prevent them from digging, is to not have the files on the machine. If they find any kind of file that appears to be encrypted, they could simply take your machine away and have it sent in for experts to dig at it.

You want safety? Send your files encrypted to the cloud and erase all traces of your online activity from your machine. Dropbox a Truecrypt file, or even consider somehting like Amazon Web services to store truecrypt containers.