You can force Windows to reject passwords that do not meet a minimum password length. Useful to help stop people from using trivial passwords where security is an issue.
Open your registry and find the key below, if the Network sub-key does not already exist then create it.
Create a new binary value named ‘MinPwdLen‘, and set the data to the minimum number of characters required for a password to be accepted.
Note: This does not apply to existing passwords, only new or changed.
REGISTRY SETTINGS:
User Key: [HKEY_CURRENT_USER\SOFTWARE\Microsoft\Windows\CurrentVersion\Policies\
Network]
System Key: [HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Policies\
Network]
Value Name: MinPwdLen
Data Type: REG_BINARY (Binary Value)
The good thing is it works for all versions of windows 
This is Shailendra,a part time blogger from India.
Sweet, I was thinking of doing this on my PC.