Can i run a GeForce GT 220 on a 160w PSU

I would not try, it recommends 300, and can draw up to 58 at load. If the PSU is marked 160, means it's putting out closer to 130, unless it's ranked at max power which most are not. Even 160 watt in true power, your system can easliy crash.

A 210 may work though.
 
To know for sure, you need to measure your total system power, find out how much is used now (with something like this http://the-gadgeteer.com/2003/12/23/kill_a_watt_electric_usage_monitor_review/)

Or you can just try one of the cards and see if it runs (I'd say 80% chance or more you will be OK with them)

nVidia 210, AMD Radeon 4350, AMD Radeon 5450, those cards should run on a 160, as long as it actually puts out close to that (power supply brand and model would help to figure that out).