hope you guys can helpthank a lot
I'm really disappointed in the advice given out here. You stated you are new to this and don't want to spend a lot. Here is the best solution:
Get this card: http://uk.pcpartpicker.com/part/evga-video-card-02gp43753kr
Plug it into your pcie slot.
Play.
It will give you around a 4x performance increase compared to what you have now: http://gpu.userbenchmark.com/Compare/Nvidia-GTX-750-Ti-vs-AMD-Radeon-HD-8570D/2187vsm9112
No PSU worries.