Here at Simple Net Security, we trust no one.
If you're unfortunate enough to have to take a laptop or computer in for repairs, remember that the technician will have access to ALL of your data.
There have been well documented cases of PC Repair shops in London copying private and holiday photos, along with log-in details on to their own computers.
We're a bit paranoid, but if we ever have to send in a computer, we make sure we back up the hard drive first, and then wipe it clean with a fresh installation before sending it away.
This is quite a labour intensive process, and won't stop real hardened criminals, but does prevent the casual PC Repair Man from snooping.
Obviously if your hard disk has failed you won't be able to do that (try Spinrite first!)