What is the System Administrator password that is prompted when opening some applications?

I adopted a eMac today from a relative as they weren't using it. It looks like a friend gave it to them who got it a garage sale. I've never had an Apple product before, I'm a pretty experienced Windows user, however. The eMac is running 10.3.3.

I went to install a USB wireless adapter (driver? are they called that on Mac?) and after it was done, I went to open it's configuration utility and it prompts this login window where it requests a password for an account called "System Administrator"

When I first got the computer, it had one account called "a a" (what a terrible name). It was an admin account, since I couldn't change its shortname, I made a new admin account called "Connor" gave myself admin privileges and then deleted "a a". Now, with this window, I enter my password and it doesn't accept it. I've tried other common passwords such as: "1234", "root", "admin", and even "password".

I'm not sure if I'm missing a default root user password. This would be much easier if the Mac OS X disc was included with the PC, but it wasn't. So, any information to help me get around this snag would be great.

Thanks!