From: http://www.practicallynetworked.com/sharing/xp_filesharing/03userpasswords.htm
Permitting Network Access Without a Password
To allow users to log onto their computers without a password and then access the XP Professional machine without a password, you must make a security policy change:
- Go to Control Panel | Performance and Maintenance | Administrative Tools | Local Security Policy.
- Expand Local Policies | Security Options.
- Double-click Accounts: Limit local account use of blank passwords to console login only, which is enabled by default. Disable this option and click OK.
This will permit network access without a password. The user’s computer can boot directly to the Windows desktop, and be validated against the corresponding XP Professional user account, without a password.
Note that the term “blank passwords” isn’t technically accurate. There’s a difference between having a password which consists of one or more blank characters, and having no password at all. This setting actually permits access by users who have no password at all.