If my user account is the administrator account, why the need for...

By default, an administrator account behaves in exactly the same way and with the same privileges as a standard account. Some programs, however, need to be run at a higher privilege level, even when run from an administrator account. In these cases, you need to right-click and select Run as administrator. Depending on the account you are currently using, you will be asked to provide administrative credentials (from a standard account) or confirm that you want to elevate (from within an administrative account).

This is part of the improved security in Windows 7, and is designed to make it harder for malware to get on your system. Of course, it isn't infallible, so you must always keep alert.

This is controlled by means of tokens, and a standard account has just one whereas an administrator account has two, a standard token and an administrative token. In normal use, both types of account use the token with standard privileges. When you right-click and select Run as administrator (see above), you are instructing the program (and that program only) to use the administrator token and to run with full administrative privileges.

From my bookshelf:

Windows 7 Administrator's Pocket Consultant, William R. Stanek, Microsoft Press said:

All applications that run on Windows 7 derive their security context from the current user's access token. By default, UAC turns all users into standard users even if they are members of the Administrators group. If an administrator user consents to the use of his/her administrator privileges, a new access token is created for the user. It contains all the user's privileges, and this access token - rather than the user's standard access token - is used to start an application or process.

MacGyvr said:

Dwarf said:

By default, an administrator account behaves in exactly the same way and with the same privileges as a standard account.

Ummmm, no. Not true at all. I'm not even sure how you would justify that statement. Try to perform some administrative tasks with a standard user account.

An administrator account (not the built-in Administrator account) is treated the same as a standard user account until the rest of his post.

Dwarf said:

......Some programs, however, need to be run at a higher privilege level, even when run from an administrator account. In these cases, you need to right-click and select Run as administrator. Depending on the account you are currently using, you will be asked to provide administrative credentials (from a standard account) or confirm that you want to elevate (from within an administrative account).

S35 said:

the "run as administrator" option? If you're the administrator, aren't all programs "run as administrator" by default?

The reason I ask is that I'm trying to delete something via Spybot, and a message appeared on the screen saying I need to run the program as an adminstrator in order to perform the deletion.

Asking such question let me think you better "run as administrator", it is only one click to do so...

Therefore the discussion here is interresting and i suggest you to stick with your "standard" account.

There's here plenty of tutorials & discuss about setting & run the OS as "standard" account or (a real) "administrator" account (last one i will not suggest).