I've had to boot my laptop at security checks a couple of times or three, but these days the security checks seems to be way too busy to go to that effort. I've never had to even show a laptop at immigration control anywhere.

As for data security, you can be forced to reveal encryption keys, and it can be illegal not to do so. To get around that can be a complex process.

To me the by far simplest option seems to be what was suggested by an earlier poster: Don't keep your important data on your laptop, or N900, keep it at the office. Use VPN to access it. For me OpenVPN works very well for this (on my laptop).