I took a look at your code, after looking at the page itself. I noticed what you were saying. There is a small space between:
After looking at your code, I noticed that you have an "HR" seperator, and a </center> tag between the Home Page link, and the list. This will cause your page to create a new paragraph, thus moving the list down further. Also, there is no need for the </center> tag, as the "HR" tag ends your first <center> tag. So, this extra </center> tag is creating a space that is not needed.
I would remove the "HR" tag, and use a 2px high single table to create the Horizontal Rule, and remove the </center> tag that follows it.
i was thinking about this, something that might be causing it. in the table holding the left column stuff, you have a paragraph tag, then a line break tag above the logo, remove those as they are pushing it down. you really don't need the div tag or center tag above that table either, you can set center and align top in the table cell that your nav table is in.
the reason for the gap at the top of the menu is because it has an image that looks about 5 pix's wide with a white background with a lin in the middle try makign the whole image one colour or make the image thiner and make it one colour this shoudl stop the problem