First of all check that your motherboard has a PCI express slot(1.1 or higher) for adding graphic card.
Then make sure you have a decent 500W power supply
Edit: According to Nvidia minimum power supply requirement for gtx 660 is 450W. But make sure whatever power supply you are using that it delivers atleast 25A @+12V rail
Cant find any psu or mobo specs for your pc. You have to check the above requirements on your own. Open your pc case and see if it meets the requirements