Clean wipe iMac running 10.4.11 OS X?

We recently bought a used iMac, (iMac7,1 running Mac OS X 10.4.11 Build 8S2167), from a garage sale.

When I plugged it in I saw that the previous owner didn't factory reset it.

He left his admin account registered with password, so I can't just erase his account and make a new admin account. Apart from this it limits me to some programs I'd like to install.

I don't have the installation disc I need (as read looking around through other forums).

And Command R is not working for me on startup. (or Control R since I'm using a Windows keyboard).

I've read that I can download a digital version of the installation program.

Can I start it up from a USB? as i do not have "FireWire" or another Mac.

If so can I have a link to the right torrent I'm looking for?

What are the steps I need to make this work...?

I have little to no knowledge about Macs, this is my first Mac.

Solution 1:

Emerald, amigo:

Let's get your Mac working for you:

1. Reboot the machine, holding down the appropriate keys on your
   windows keyboard to effectuate an Apple COMMAND-s. Two keys here, the 's' for single-user, and whatever key maps to the COMMAND, or APPLE key. If all goes well, then a nerd-screen, like a DOS prompt or UNIX shell will appear instead of the normal boot process.

2. Please execute the fsck as it is suggested above your command prompt.
   Should be something like

         /sbin/fsck -fy
   

3. Let's mount the root partition in read write mode:

         /sbin/mount -uw /  
   

4. Carefully delete the one file in the way of your enjoyment of your
   new Mac -- no re-installation shenanigans required:

        rm -f /var/db/.AppleSetupDone
   

5. Proper restart:

        sync ; shutdown -r now
   

Next, create your new admin account, as if this was the first time you ever used your new Mac.

Enjoy,

F.

Solution 2:

The best way to get this Mac up and running will be to do an erase and clean install of the latest Mac OS from a bootable USB installer, which someone else with a Mac running a recent version of Mac OS can prepare for you by following the instructions here.

If you can't find someone to do this as a favour then an Apple Store may be able to do it for free or a local computer repair shop that knows Macs should be able to do it at low cost - although you might need to be able to provide proof that you legitimately own the computer.

A cheap and worthwhile upgrade to this machine would be to install a 4 GB RAM module in one of the two slots to take the installed RAM to the maximum 6 GB - RAM and other specs for this family of iMacs can be found at everymac.com (example).