why creating slice tables?

I'm building my first web site ever.
I'm reading that I can use Photoshop and Image Ready to prepare the page to Dream Weaver treatment. In few words, what it takes to be done is to divide the Photoshop image in slices, which will correspond in cells in Dream Weaver.
It is given the opportunity to group several slices in a table before exporting them all to Dream weaver.
I wonder: what's the use of creating this table before that Dreamweaver creates its own table including the slices as cells? In other words: why to include an ImageReady created table into another one created by Dreamweaver. Which advantages does this procedure imply?
thanks to all,
Giuseppe, Rome
I'm using Photoshop CS on a PC

what's the use of creating this table before that Dreamweaver creates its own table

The benefit is that ImageReady will calculate the width and depth of each slice for you. It really is quicker to use the IR code.

The benefit is that ImageReady will calculate the width and

depth of each slice for you.

If you consider it a befefit to create messy, bloated code that is often a disaster in Dreamweaver. Only use Photshop to create graphics. Do everything else in Dreamweaver itself.