My Favorite Pwr solution is dual, hot swapable 350watt power supplies, should be enough, together they are 700 watts, mine has an alarm should on of them fail, and if I am not there when it fails, my OS monitors the CPU temps and voltages and will shut the system down shoul the mobo start pulling more current than the pwr can supply, and this supply is cheaper than a 450Watt single unit. This is what works for me, your application may require more power, I am running 2 eide hard drives, 2 CD-ROMs 1 is a burner, a similar video to yours, a USR internal modem, Sound Blaster Live audio, and an intel Pro100+ Server NIC card, on a GigaByte GA7ZX MOBO with a 1.2gb Athlon Thunderbird CPU.
Not that this will help much, allen's advice is definately safe, and aj's requires some study, all are good advice...just my 2 cents worth.