This is a good synopsis of the three grades of locks generally used in a residence or office.
http://www.ehow.com/info_7871533_do-lock-grades-mean.html Just replacing the cylinder with a better one only helps somewhat. TO get the full advantage, the whole assembly must be adequate for your needs. Picking resistance in the lock is only one aspect of a lock assembly's security.
Last time I checked, Medco had three options on key security:
- a one-time build of the lock and keysets...not able to buy additional new keys ever
- a restricted means of acquiring additional keys...must provide the CC like card that authorizes additional keys to be honored which is coded
- additional keys at will from an authorized Medco dealer