i doubt it would be a good idea to use that card in your PC with a 160W PSU even if 160W is enough, because a 160W PSU is really small in the first place, so you should just upgrade it anyways.
This is about the best you can do with your current power supply: ECS GeForce 6200 256MB 64-bit DDR2 AGP 8X . It's really not too much better than your on-board though.