Welcome to the Intel® Embedded Community. Our community is focused on embedded applications and the issue you describe pertains to a consumer PC. So you are really not in the right place to solve your problem. Your best avenue for support for your Dell PC, including driver updates, is to contact Dell directly. http://support.dell.com I personally have a Dell PC and have found good success with Dell support.
You might also try this Intel site that deals with graphics issues: http://www.intel.com/support/graphics/sb/CS-028366.htm