Is it easy for a 70 year old to replace a nVidia graphics G Force 5600 with a 9600 in my five year old desk top, will I have to buy software or can I just download the driver.
It's relatively easy to change a graphics card, providing you have the same connections on the motherboard.
As far as I can see the NVIDIA Geforce 5600 is an AGP connection and the Nvidia 9600 is a PCI Express connection, so in your case unless your Motherboard has both connections (unlikely) you cannot do a direct swap.