I have an Dell dimension E521 which has 2 slots for cards but i think 1 is being used by a very ordinary graphics card (which i was planning to replace with the Nvidia 8800 GTX) and the other a sound card. Is there a way i can make more slots or do i even need the sound card? and also would someone be able to tell me more about how to upgrade the power supply and add a water cooler to the GTX (if i get one)..?