You wish to setup an automatic logon (all but eliminating the advantages of
having a password protected account)...?

Automatic Logons:
------
Microsoft method:
http://support.microsoft.com/kb/315231
(Essentially the same... but different place:
  http://www.pctools.com/guides/registry/detail/13/ )

Microsoft Method 2:
TweakUI from:
http://www.microsoft.com/windowsxp/downloads/powertoys/xppowertoys.mspx

control userpasswords2 method:
1) Go to the Start Menu and the Run box.
2) Type in the following:

control userpasswords2

now click OK
3) In the new Windows that appears select the account you wish to make the
primary logon.
Now uncheck the "Users must enter a username and password..." box.
4) Hit Apply and a dialog box will appear asking you to confirm the selected
users password.
Click OK when you are done...
------

Hopefully that gets you where you are wanting to be.

It is a *good* thing in the user arena to:
1) Have strong passwords.
2) Have more than one administrator level account (with strong passwords).

In principle you could poke the values into the registry winlogon key, then
remove them after reboot. Requires a bit of scripting work but shouldn't be
too hard.

http://support.microsoft.com/kb/315231

In fact you just need to null the Default Password to stop autologon, the
other values can remain.