What about admin passwords and infections?

Link (PDF)

Without admin password set does mallware have free access?

What is that admin password? Is it my user's password too?(my user is admin type.)

If tere is a user with no password can mallware infiltrate through it?

 

OK so if it is shared.
Windows:
LAN shared? Like through File and Printer Sharing for Microsoft Networks?

On linux I saw a guy entering random IPs and he logged on into a system being able to do whatever. Can the ww net be used to logon to windows? I disabled the checkboxes and services, is there something else on my winxp?

There is talk about the administrator account.
Is there a main one that's higher than my own only account, which is of administrator type? If so are they merged in any circumstances?

Please recommend (admin password)security in max 5 words.:confused