Your setup is not secure at all. The greatest risk is not theft, but that your monitor catches fire and destroys both the paper backup and the harddisk. I am serious! Although theft is a possibility too.
Paper wallet security has two aspects: the risk of theft and the risk of accidentally losing the wallet. Both are real, but the latter is probably the most common.
A single paper backup in your home is pretty secure against theft, as most thieves will not sift through your "worthless" papers. But you are vulnerable to fire or other accidents ruining both the computer and the backup.
Several copies of the backup helps, but now the risk of theft goes up. Don't store an extra copy in the office if you constantly tell your colleagues how great bitcoins are.
The N-of-M backup is the most flexible. Good ways would be a
* 2-of-3 with one copy in the home, and two copies with people you trust. Now they need to conspire to steal your coin (and no need to tell them where the other copies are). If one of them is careless and loses his copy, too bad. This is what I do.
* 3-of-5 with one copy in the home, two in a safe in the bank, and two copies with trustworthy friends (or even one in the office, one with a friend/family). Now you can restore even if both your friends lose their copies. And neither your friends nor the bank can take your bitcoin. Of course most of us do not have the amounts of bitcoin requiring this kind of care. Unfortunately.
How NOT to do it: A 6-of-6 backup, stored in six safe places. No-one can steal your coins, but if just a single copy is lost, all is lost.
TL;DR: Make a mental list of good, independent (= not likely to burn in the same fire) places to keep your backup, and make an N-of-M backup accordingly.
