I would say be careful. PCI-Express 2.1 cards had some weird compatibility issues with 1.0 slots at the time of socket 775. Also if you wouldn't mind could to take your side panel off and take a look at your power supply. I would like to know what you have.
Are you gamer?why such low end card.i reccomend go with nvidia as nvidia has pci exp 2.0 whereas amd has 2.1.pci 2.0 have no problem in pci 1.0 but 2.1 has problem with 1.0.get atleast gt 630 or gt 640.