

A related issue is that such users have the ability to perform actions that could lead to operating system instability or corruption. This is because all programs run, by default, using the security permissions of the user who launched them. The primary issue is that unwanted software can make changes to the operating system or to data without the user’s permission.

There are potential security considerations for users who use an administrative account for daily computer use. Regarding Windows, then its fair to assume that Microsoft know something about it - here is just one quote from their info pages. There are so many differing views on the web it can be hard to know what valid you can drive yourself mad looking at all the opinions.
