What passwords are you talking about?
If someone has physical access to your computer for some time, unless you encrypt the drive, no password system will help you.
If you mean people cracking into your system from over the internet, then you should do a number of things.
Use KeePass to store and generate passwords for you:
http://keepass.info/
Then you just have to remember one really high-security password.
Use different passwords for all the differnet sites and applications you use.