If your pc is DC'ing 1 toon and running at 100% either your cpu or power supply need upgrading. I wouldn't recomend overclocking as it shortens the life of your chip. But cpu's are cheap now a days, if your not already I'd spend the 180$ and get a quad core. But make sure your power supply is at least 500w. A "stock" power supply is usually 300 which isn't enough power for your system when its using massive resources like running mulitple clients.