power supply

I started looking at the past threads and now kind of wondering if I have enough power supply for my unit it has:

Itel dual core two fans with lights
processor fan
Case lights
dvd burner
multi card reader
sata 7200 drive
low rent video card ha ha ge force 7300 gs
tv tuner card
volume gauge
processor temp gauge
fan speed gauge
and was thinking of adding another dvd burner
thinking maybe go around 500 to 600 watters for the better amps
any input will help thanks