??? I'm not sure exactly what you mean. In order to use blank passwords,
just don't use a password. If you only have a few people and computers,
that might work. It really isn't preferable to use null (blank)
passwords when networking.
Maybe you should post back with a better description of your network and
your end goal. It can be very hard for a non-technical person to know
what to include in a post to a tech support newsgroup. Here is a link
that will help you with that - 
http://www.dts-l.org/goodpost.htm