Thanks for the reply Thelma.
I totally agree - it would be a lot easier for the person to use the back button,
But my experience with customers and ordinary joe bloggs is that they will close when current window expect to see your site and not to have to use the back button.
A possible scenario -
1) When on the external site - you could end up going further and further into the site viewing products and details etc,
and I know most customers will not want to have to press the Back Button so many times to return to our site,
And after finishing with the external site, they will automatically hit the X to close and expect to see the original site.
if not opened in a new window there is the fear of not returning to our site.
Hope I make sense with my mumbo jumbo above
Is it a big task to include this on a website?
Thanks again.