Computer Issue Help ?

Okay so my motherboard is an ASROCK N68C UCC , it has Nvidia Geforce 7025 / Nvidia nForce 630a Video Card now I'm looking to update this to a 1GB Nvidia Geforce GTX 280 which plugs in through the PCI express slot now if I try to upgrade will any problems spring up like none compatability , or lack of power supply or is it even possible to upgrade on from an intergrated Graphics Card to a Dedicated One? basically the question is can I upgrade I mean here's some more idea of my Pc's spec , Athlon AMD 3.00 GHZ (Dual Core) , 4GB of RAM, 500GB HDD.