This is a thing I've seen today from a customer. They have only an Administrator account on their Windows machines and they use this account to do all the possible tasks.
I don't agree to this choice. You shouldn't use the Administrator account to perform all your tasks. In this case "Unix Docet": you should have an Administrator account and a User account for everyday use.
The best way is using the User account for the normal usage of your machine and use the Administrator account only when you have the necessity to do tasks that requires the administrative privileges.
When you need to perform this type of tasks you could also use the Runas command, a command that restricts the administrative privileges to the task that you're performing (the same thing you are doing with Unix with the su command).
By typing something like:
runas /user:<local machine>\administrator MyTask
or
runas /user:administrator@<domain name> MyTask
you can run a task respectively with local administrative privileges and domain administrative privileges.
Having only the Administrator account is (in my opinion) dangerous... I don't want to imagine what could happen if a secretary of my customer log in to the server with the Admin account and start working... 