actually im buying a completely new pc not upgraing that one my budget is 20k pkr in pakistan imma also buy 750ti if money is leftYou're going to need to replace the motherboard and(possibly) the ram if you want to go outside of the LGA775 socket.
You might also want to shoot us a budget and your location for ease of sourcing parts.
20000 pkr in pakistan possibly i will also try to get a 750ti