lammert - 9:50 pm on May 24, 2011 (gmt 0)
For laptops you can buy special laptop safes. My experience is that laptops don't fit well in ordinary safes. Having a steel cable between your computer and the furniture may help to prevent it from being stolen by a shark, but any thief with serious equipment will be able to cut the cable or lock and take the computer with them.
I have seen permanent anti-theft enclosures for running desktops and small servers which have a forced ventilation system to keep the computer cool. But in such a situation I would rather go for a locked room and put the server there.