How to reenable video driver on laptop

Hi all I had a moment of smarts. Linking up a laptop to a stand alone display. As it did not work first time I decided to switch off the video adaptor. What I now have is a laptop that boots, jumps into xp pro and then shows a blank screen. Any ideas?

I have tries booting in safe mode that generates a long stream of text ( driver info I guess) then stops.

And ideas gratefully received