You can try getting the Geforce GT210 or the GT220
Both draw 22 watts and 45 watts at full load, respectively.
A word of caution though. With the GT220 your PSU would be put very close to it's maximum load everytime you game, and the longer you put the power supply to the limit, the higher the chances of it failling.
The GT220 in a benchmark test, was tested in a system with GPU in FULL Stress = 212 Watts
and you only have 220 watts. It's usually a better idea to have at least 100 watts more than you need just in case your power supply does not deliver a constant 220 watts (it actually fluctuates up and down, as many cheap power supplies do).
I'd recommend upgrading the power supply to a 400 watt unit (or even a 500 watt, you can use this power supply in your next computer)