This really needs more information.
Model on the P4. Make, Model, and Speed of the RAM. Make and Model of the video card. Make and model of the drives.
If you are going to attempt to sell computer components, please be aware that a majority of informed buyers will need such information to make a decision. Particularly for the RAM as the wrong type will blatantly not work. But the other information is just as important as there can be a vast difference between brands and models of the same item.