Video Card for XPS Made in 2006

I have a Dell xps laptop made in 2006.  The video went out even when It is connected to an external monitor.  It will show on the external monitor and laptop monitor the diagnostic tests as they are being run but will then go black and will not show anything.  A tech not associated with Dell tried to tell me that I should buy a new one because this one is too old.  However, having paid four large for it and finding it as powerful as most large desktops and indeed the very best laptop I have ever had the pleasure of using, I would prefer to fix it and keep it.  A
Dell tech told me it is capable of running windows 7 and will also take up to a 1 gig video card which based on his view is probably all I need, a new video card.  But what kind, where can I find one and Dell does not seem to have a parts list or if it does I cannot find it that will allow me to order one.  Can anyone help?