Basically you CPU acts as a "organizer" in your computer. It calculates information as well as gives tasks to other components in your system.
correct, my current video card is a PCI express X16. I'm sorry I'm not quite understanding your last reply about the CPU (X2 4200+) will prevent the newer card from performing at it's best? how come?
So what happends when you place a high end GPU with a mid range CPU?
Well since your GPU is much more powerful then your CPU, it can calculate information faster then the CPU can send to the GPU. So basically your GPU works at lets say, 80% capacity instead of 100%. Please note, I that 80% is a random figure and will go up and down depending on the combination of parts.