In Windows XP you can set criteria reagrding the length
of a password.You can specify a minimum password length
below which all shorter passwords will be rejected.
To do so follow the path below :


- HKEY_CURRENT_USER\SOFTWARE\Microsoft\Windows
\CurrentVersion\Policies\Network\


(If you need to create the Network subkey right click on Policies ,
new , key , name the key : Network)


Create here in the right pane the entry :

MinPwdLen

(create : right click , new , REG_BINARY [Binary Value] and name it as above)

Doubleclick the entry and set it's value to the minimum password lenght
you want to set.

Log off / Log on !