'Offline passwords guessers have gotten both fast and smart. AccessData sells Password Recovery Toolkit, or PRTK. Depending on he software it is attacking, PRTK can test up to hundreds of thousands of passwords per second, and it tests more common passwords sooner than obscure ones. So the security of your password depends on two things: any details of the software that slow down password guessing, and in what order programs like PTRK guess different passwords.