Kris - you posted about a different eMac issue, the noise from the screen. I checked back to that, and can't find any reference to which model of eMac you have. Can we have those specs please. If it's an earlier eMac, and you've loaded Leopard on to it, it's going to struggle, both with processor speed and graphics card. We'll know better once we know more about your eMac.
Incidentally, in case you're not aware, you can get the eMac specs from the menu bar >blue apple > about this Mac. Or use System Profiler.
Edit: are you in the UK?