Power Supply when Building your own Computer

i just bought $1100 worth of computer parts and realized that am pretty sure the power supply i have right now isn't gonna support what i am gonna be running.

I am getting a ASUS A8V motherboard and a AMD athlon 64 3500 processor. Any idea of where i could find out what i need to get for the supply?

You'd probably be safe with a 400 - 450 watt power supply - I'm not sure if the 64s suck any more power than what a 32-bit would use, but as a rule of thumb, higher than a 450 seems to be overkill.