That's true. If your PSU is a POS then it isn't worth using in the new build unless you want to risk fried components. I've never heard of "Earthmate" power supplies. The chances are very good that it's a POS that would be better used as a door stop.
The L3 cache doesn't make a huge difference. Check any of the benchmarks for confirmation. The new Athlon chips offer great performance for the money. Going to a Phenom II would cost considerably more which puts you further over budget with very little performance gain. I think the Athlon chips offer the perfect bang-for-buck considering your budget.