Password

If you are in a 'domain' you can't do it. (well, you *could* go to www.tucows.com and get tweakui (shudder) and it will do an auto logon for you but your net admin might choke you (smile))
If you are not on a network, or if you are on a 'workgroup'network, you can do the steps below (below pasted from microsoft knowledgebase article #234562)
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Preventing the Password Prompt in a Non-domain System
In Control Panel, double-click Users and Passwords.
Click to clear the Users must enter a user name and password to use this computer check box.

NOTE: This option does not appear on a system that is a member of a domain.
Click the Advanced tab.
Click to clear the Require users to press Ctrl-Alt-Del before logging on check box.
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let us know if you don't know if you are on a domain or workgroup or want more help...good luck.

If you are in a networked enviroment the administrator might have a block on that action. Otherwise you can do that with tweakui.

Lee