The driver you downloaded is for a different controller so; that definitely will not install in your computer. This is the link to the correct graphics driver http://downloadcenter.intel.com/Detail_Desc.aspx?agr=Y&DwnldID=9033&ProdId=865&lang=eng&OSVersion=Windows%20XP%20%20Professional*&DownloadType=Drivers.
If issue persists I recommend installing the monitor driver. This link will help you to know how to get the monitor driver
In case the issue persists I recommend getting in contact with DELL so; they can give you more advanced support.
Thanks for your reply.
The driver you have linked to is the one that I am currently using and is the one I am having the problem with.
You say the driver I downloaded is for a different controller so; that definitely will not install in your computer but is the one that is recommended by Intel. See this link. Graphics — Unable to use the native resolution of some displays
This is supposed to be a solution to the problem but I can't install it.
My monitor is a Hanns-G HW173A and there is no driver available for it that I can find.
Any further input would be welcome