When I travel, I lock up my external 500G e-SATA drive or take it with me. My desktop has programs only in its HD (“C” drive). Once you log in as a “guest,” there is nothing to “see” here so move on.
I have a major issue w/privacy, because I work on legal cases prior to trial. And I MUST have “house-sitters” because I have pets.
If I need photo files to show for leisure on a trip, I have 4 “thumb drives” (up to 4G) which I can take with me.
I have never used online backup systems.
edit: Oh, and my laptop has “programs only” in it. It will be boring to anyone who successfully “steals” it.