In Windows 7 and Vista, Administrator account login is disabled by default to protect the system in all clean installations. However, it is enabled for upgrade installations where there is no other local Administrator account on the computer.
If you want to use Windows 7 the way that you want just like in Windows XP (no UAC), just enable the Built-in Administrator account.
How to Add Administrator User to Welcome Screen
1. From the previous vista article, simply open the command prompt as administrator: Start Menu > type “cmd” > Right-Click Menu > Run as administrator or simply press CTRL + Shift + Enter
Read more: Don’t forget to check the complete article in opening a program with Administrator Privilege in Windows 7
2. Input the following command: Net user Administrator /active:yes
User Account Control (UAC) and protected mode in Internet Explorer is Off.
Recommended for technical users only.
Enjoy using Windows 7!