Firstly you need to get an idea. Read this thread completely: *www.thinkdigit.com/forum/graphic-c...ormation-regarding-graphic-cards-newbies.html
Second, I can't seem to find the specifications of your motherboard on the internet. It should have a PCI-express slot, but are you sure? You need to only have a PCI-express slot to run a graphic card. Which processor do you have?
The PSU which you have isn't a good one. Max what I'd suggest you to run is HD 6570, HD 5670 or HD 6670. Don't go beyond these as your power supply isn't a good one. HD 6670 GDDR5 retails for $90.