most password guides suggest that using a huge combination of random alphanumeric characters (eg. D&+3@dGk% ) is the only way to create a secure password .. these are hardly usable passwords ... people end up using short, easily cracked passwords.

a better solution is to use a passphrase ... according to http://lastbit.com/pswcalc.asp , a passphrase consisting of 13 (only) lowercase characters would take almost 8000 years to break checking 10 million pw/sec ...

the ubuntu installer could use the word list on www.diceware.com (which also has a lot of information on passphrases) to generate a random, secure passphrase ..