As long as the power requirements for the rest of your system are less than 150W then theoretically "yes". Though 500W for a graphics card seems a lot. Are you sure that the requirement wasn't for a power supply rated at at least 500W?
In that case a 650W PSU is more than enough.
In general, when dealing with power it's advisable to have a buffer between the maximum power requirements of your system and the peak power (which is the value quoted) that the PSU can deliver.
So add up the requirements of your system:
- Hard drives
- Optical drives
- Graphics card
Add a buffer (10%?) and if that comes to less than 650W you should be OK.