Hi,

WindowsXP creates an Administrator account by default. This account is
normally hidden and is intended as a reserve account for troubleshooting
purposes and not meant for day to day use. As long as there is another
account created with administrator credentials the default administrator
account will remain hidden. The hidden Administrator account that you had
been using can be accessed pressing Ctrl+alt+del twice at the welcome
screen. For the user name type administrator and enter a password if there
was one. If there was no password leave it blank and press enter.

You will have to choose a name other than administrator for the new account.

User data can be copied to the new account using this article.
How to copy data from one user profile to a new profile
http://support.microsoft.com/default.aspx?scid=kb;en-us;811151

If there's a email program containing your email that you need also, let us
know what the name and versions of the email program so we can help you further.

Regards,
Bert Kinney MS-MVP Shell/User
http://bertk.mvps.org
Member: http://dts-l.org

Don't Turn it off. If you want an account for casual users, create a new
Limited User Account and call it "Visitor" or some such.

    As you've discovered, once any additional user accounts have been
created, the built-in Administrator account will no longer be displayed
on the Welcome Screen.  This is a default security feature.

    The built-in Administrator account really was never intended to be
used for day-to-day normal use.  The standard security practice is to
rename the account, set a strong password on it, and use it only to
create another account for regular use, reserving the Administrator
account as a "back door" in case something corrupts your regular account(s).

    By design, the only way to log into the Administrator account of
WinXP Home is to reboot into Safe Mode.  For WinXP Pro, pressing
CTRL+ALT+DEL twice at the Welcome Screen will produce the standard login
dialog box.

    A wiser course of action would be to create another user account
for your daily use (as you've done), and copy desired the files and
settings from the Administrator account to this newly created user profile.

HOW TO Create and Configure User Accounts in Windows XP
http://support.microsoft.com/default.aspx?scid=kb;en-us;279783

How to Copy User Data to a New User Profile
http://support.microsoft.com/default.aspx?scid=kb;en-us;811151