How secure is your office infrastructure. there were software locks on security, now there are hardware locks on security.
Some companies allow employees to use office infrastructures like printers et al for their limited personal work, some other companies strictly consider it as a threat. For the latter category here is a news update.
You have hard disk with number pad for creating passwords of 6-20 digit strength and give an additional layer of security from employee theft of valuable corporate data( Encryption being one). So apart from other devices like printer which gives such lock security .
Apart from that consider using CCTV surveillance of employees as it creates more discipline in employees. Self discipline is the best but then any system left to it self leads to entropy.
So take your security policy decision today.