To answer your question, Yes, you could in theory. For this situation however, you should certainly not do that. The age difference in these parts is such a gap that you would run into and infinite number of "bottlenecks" (One part holding back another) My advice is to re-install Windows on both of them, assuming the BSoD is software related. Also, to fix the fan in the Dell, I would recommend getting some compressed air and blowing out dust, then replacing the thermal paste between the CPU and CPU heatsink. LGA775 CPUs can be quite the furnace, especially the Pentium D. I don't know where you heard that adding a Graphics Card would reduce fan noise, but that is not true. It would be another fan and another source of heat, while it may reduce strain on the integrated graphics, it would ultimately be louder. I hope that helped you out, if anything is confusing, feel free to ask for more help. Best of luck!