Getting into the computer

Hi Everyone,
I must admit I'm a complete newbie when it comes to Macs but I'm also in charge of all the tech for a project in Nicaragua and so here is my problem.

We were just donated someones old iMac for the kids to use in our program. The previous owner, however, left their account and password on the computer and we can't use it for anything. We got in touch with the person who donated it and he has no idea what the password is either and we don't have a Mac OSX disk to try to recover account.

Now, researching ways to get around this password problem I came across the following

Reboot
Hold apple + s down after you hear the chime.
When you get text prompt enter in these terminal commands to create a brand new admin account (hitting return after each line):
mount -uw /
rm /var/db/.AppleSetupDone
shutdown -h now
After rebooting you should have a brand new admin account. When you login as the new admin you can simply delete the old one and you’re good to go again!

I tried this and it didn't seem to do anything but when I restarted I didn't even get a log in screen. I just get a gray screen with an Apple logo and a little circle thingy that keep going around and around.

Any ideas?

Thanks,
Mark

Purchase an OS X.4 disc however if it Firmware Password Protected no answer at all. Do you see the padlock halfway down this page?


http://support.apple.com/kb/HT1352

Hi Harry, it is not Firnware Password Protected from what I can tell and the fact that we are in Nicaragua makes it rather difficult to just "purchase" an OSX disk. I would also be quite happy to restore it to a state that asks me for the password again. The original owner was still going to try to figure out what that password was, we were just getting a little impatient.