Double and triple check everything before purchase
It's the best way to avoid surprises and unexpected costs.
Your PSU (power supply unit) needs to be AT LEAST 500W with two 6-pin connectors. Note that 450/460/470/480 are power-hungry beasts and can easily fry cheap PSU-s :P
4xx series heat up really fast, pay some attention to the case ventilation too.
460 will do just fine for your needs.