During the normal use of your computer, you should not run the system as an administrator level account.
If your system is ever compromised, the intruder, virus, malware, etc. will have the same rights as the account that you logged in with. If that account is a member of Administrators group, then the intruder will have total access to your system to do with as they wish. If that account is not a computer Administrator, then you've limited what the intruder has access to, which may be enough to limit the intruders access and the amount of damage that they could do.
HOW TO: Create a Custom Default User Profile, describes how to create a custom default user profile in Windows 2000 & XP. A custom default user profile is helpful if several people use the same computer but each user wants a separate profile along with access to shared resources.
Regardless of which operating system you use, all user accounts should have a password set.
By default Microsoft Windows XP Home Edition, does not prompt to set a password for the Administrator user account during installation. There's probably no password set for Administrator enabling anyone to log into your computer.
After you log on as an administrator to a computer that is not a member of a domain, when you double-click User Accounts in Control Panel to change the password for the built-in Administrator account, the Administrator account may not appear in the list of user accounts. Consequently, you cannot change its password.
This behavior can occur because the Administrator account logon option appears only in Safe mode if more than one account is created on the system. The Administrator account is available in Normal mode only if there are no other accounts on the system. To work around this behavior:
- If you are running Windows XP Home Edition, restart the computer and then use a power user account to log on to the
computer in Safe mode.
- If you are running Windows XP Professional, reset the password in the Local Users and Groups snap-in in Microsoft
Management Console (MMC):
1. Click Start, and then click Run.
2. In the Open box, type "mmc" (without the quotation marks), and then click OK to start MMC.
3. Start the Local Users and Groups snap-in.
4. Under Console Root, expand "Local Users and Groups", and then click Users.
5. In the right pane, right-click Administrator, and then click Set Password.
6. Click Proceed in the message box that appears.
7. Type and confirm the new password in the appropriate boxes, and then click OK.
The firewall that's part of Microsoft Windows XP Service Pack 2, only blocks incoming connections and does not block outgoing connections.
I recommed that you get a firewall that does two-way, inbound and outbound, blocking. (e.g. ZoneAlarm, Comodo Firewall)