Notebook graphics chips cannot be upgraded. They are chips soldered onto the motherboard. The motherboards are custom sized in each notebook with no standardization so you cannot upgrade the motherboard either.
Can you give us details of your situation? Perhaps we can find an alternative?http://www.dell.com/us/en/dfb/notebooks/inspn_b120/pd.aspx?refid=inspn_b120&cs=28&s=dfb