At about 2 minutes, 30 seconds into this video......
http://www.youtube.com/watch?v=nBhOjWHbD6M
....they show how easy it is to break into even a high dollar (for a homeowner) safe.
Who exactly are you wanting to keep out?
I can break into any home safe with a circular saw and masonry blades, assuming I have enough time and can access the safe's sides.