What's a recommended setup of accounts on Mac OS X?

All actions taken on a non admin account that would need admin privileges require the user to enter the name of an admin account and the password before continuing.

So if you download software on a standard user account, when you come to install it you will be asked to enter the admin user name and password.

I use the admin account and my girlfriend has a standard user account. She can import music, photos download apps from the app store, she can change system preferences in the settings panel but not alter the status of my admin account, create accounts, etc, etc.

I have not heard of this procedure of using a non admin account as to do anything that will change the system as you are required to enter the password anyway.

I have a separate admin account that I only use for installing and updating applications and the OS, and making other system configuration changes that require it. My day-to-day account does not have admin rights. The two accounts have different passwords. I never type my admin password to change things from my user account.

This extra step (having to switch to the admin account when necessary) makes it far less likely that some typo, sleep deprivation, or accidental click will even try to change some system setting, file or install some unwanted code. I am far more careful about everything I do when logged into the admin account, as there are many more ways to make your OS crash and you Mac unbootable when logged in as an admin.

But when needed (and when you are awake enough for the extra step), it's easy to log into the admin account to install stuff.

Matt, your's is a good usage practice ;)

Take a look at Rui Carmo's excelent Switch to the Mac Howto

excerpt:

Don’t use the administration account for anything other than setting up the machine and applications or changing “permanent” settings (if you want to, say, change network settings as a normal user you’ll be prompted for the admin password, and since you’ll do configuration changes less and less often as time progresses, this isn’t a problem).

If you want install some opensource tools use Homebrew instead of Macports or Fink