the simplest form of "Hard to break" password consists of 2 real words with a string of punctuation / numbers in the middle.
Long, strong, and soft on the brain too. eg.
Fishing&^%Barbecue
Others involve taking full sentances and usign leading letters, comverting some into numbers using standard l33t conversion. eg:
(real old root password for Easynet
"Sky broadband is turnign into a support nightmare"
becomes:
5bb1t145n
However, if you wish to generate totally random passwords, check out
WAPG - Available to download from the download link on that page.
I've never been a great fan of Password managers. However if you are set on one, then i'd sugest using a seperate mesium such as a PDA / Phone (Blackberries have a password keeper on them) rather than storing the password keeper on the same computer as the resources.