Swiss Cheese Security

Which of these network environments is safest from malicious damage?

Site A:
- web mail sites are blocked
- social networking sites are blocked
- cd/dvd-rw drives are not controlled
- usb devices are not blocked or encrypted

Site B:
- web mail sites are not blocked
- social networking sites are not blocked
- cd/dvd-rw devices are automatically encrypted or blocked (if not encrypted)
- usb devices are automatically encrypted or blocked (if not encrypted)

Ok, and for added entertainment, see if you can pronounce the title of this article out loud ten times as fast as you possibly can (without screwing it up).