thanks for the reply Rich,
whilst that function is useful, it is not the same as the middle click function that I'm searching for. Doing a middle click on a link on a browser opens that link in a new tab, and is thus much quicker than doing a right click and then selecting "open in new tab". The middle click also allows you to easily close open tabs with a single click.
On a dedicated mouse- the middle click is performed by pressing the scroller button, and on most laptops you can emulate it by pressing both the left and right click buttons at the same time. however, on the new sony vaio's there are no separate buttons for left and right click
so i dont know how to do a middle click. it's really frustrating that laptop manufacturers dont think of this