How can I configure Windows XP to automatically log in the most recent
user again upon reboot, without requiring any user intervention
(specifically, clicking on the user icon at the welcome screen--I've
already turned off the password feature)?

I couldn't find anything on XP but here is how you do it with NT..

Maybe it will work??

Darren.
----------------------

To enable this feature you need to add several new values to the
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows
NT\CurrentVersion\Winlogon key:

Add a new value of 'DefaultUserName' and set the data to the username
you wish to automatically logon as.
Add a new value of 'DefaultPassword' and set this to the password for
the username above.
Add a new value of 'DefaultDomainName' and set this to the domain of
the user. Ignore this value if the NT box is not participating in NT
Domain security.
Add a new value of 'AutoAdminLogon' and set it to either '1' to enable
auto logon or '0' to disable.
Exit and reboot, Windows should not ask for a password and
automatically show the desktop of the user.
Warning: The password is stored in the registry, which means anyone
who has access to the machine has access to the password

There is a free utility, TweakUI for Windows XP.

(http://www.microsoft.com/windowsxp/home/downloads/powertoys.asp
or
http://download.microsoft.com/download/whistler/Install/2/WXP/EN-US/TweakUiPowertoySetup.exe)

Install it and then start it from the Control Panel. Go to Logon tab,
check the "log on automatically at system startup" and then provide
your user name and password.

Unfortunately, this will be for a specific user and not the last
logged in user. You can set this feature if a particular person is to
useing the PC formost of the time.

Also, this is a easier way of doing the task commented by dmoore-ga.

Regards
Vipul Patel