You have quite a lot of errors in your code, but one that is causing at least half the empty space is in the left hand column, right under the bit about "Independent Fanuc/Gefanuc Parts Supplier..." etc. You have a whole bunch of <br> tags, followed by some empty <p></p>'s. Get rid of all that for a start, then try tidying up your code. Make sure all your tables are nested properly. I suggest printing the source code out and going through it with several different coloured highlighter pens.
Glad it's fixed topboy, but I've beeng going though the same thing, also with Dreamweaver (2). Instead of using paragraphs as empty containers or <br> in that left column, I made a transparent gif 5 pixels wide so that I can easily adjust the height of it. I can put a border on it while working on the site so it can be seen and just remove it when I'm done. That gif keeps the part up top that's supposed to be on the left side, whether it's buttons or link text.
I found that the biggest part of the problem is that Dreamweaver inserts the height in tables as the default, so I've had to keep going in and removing that part of the code every time.
Marcia, as you say, Dreamweaver can be tricky in that respect. Neil has fixed his problem differently, but another way round in that specific case would have been to set the vertical alignment for the content within the cell to the top - this should have kept the content in place (default is middle for Dreamweaver 3). Not sure if this would be of any help for you though - may depend on layout.