You may need to install your chipset driver first so windows can see what cpu it actually has, also complete all windows updates/optional updates... or crack onto the dell site and input your serial number and it will give you a list of drivers....
I know with some units when you have the wrong driver (GPU for example) It will say that you don't meet the minium requirments.
1. Install all updates
2. Make sure you have the correct drivers.
Dell serial number Driver download:http://support.dell.com/support/DPP/Index.aspx?c=us&l=en&s=gen