Thanks a lot . But I can't afford a Corsair or Antec etc ... No money . My PC dealer suggested me Mercury 450 watt will that be okay ?
Never heard of it, so chances are it's crap, which means it may ending up costing you a lot more in the long run if you need to replace other parts due to failure.
Some decent lower cost PSUs are Antec Basiq or OCZ, or Seasonic SS.