Big Gap in IE

[BossLovely]

I'm having the hardest time trying to figure out why this page: http://www.caprojectconnection.org/exhibitor.html has a big gap in between the first header and the table when it is viewed in Internet Explorer.
I had this issue before on this page:
http://www.caprojectconnection.org/sponsorship.html and I realized in the HTML the cellspacing in the table was set to "20". When I reset it to "0", the page displayed fine in IE.
However, on the Exhibitor page, I did not set a spacing or a padding to the tables and I cannot figure out in the code (both in the CSS and HTML) why there is a big gap. The page displays properly in Firefox. Can someone tell me why there's a gap? I would greatly appreciate this....
Thank you so much!!

[Centauri]

When you start with the width of the paypal image at 400px, add the input padding, the form padding, the form margin, the td padding and border, the table actually comes out at 441px wide, and adding the table margin and IE6's 3px jog bug (both sides), the total is too wide for the #main div. The margins on this div seem to be reversed anyway taking into consideration the sidebar divs, and altering the margins appropriately gets things happening:
.three-col #main {
margin: 10px 200px 0 180px;
}

[BossLovely]

you ROCK!
thank you! it worked PERFECTLY...so IE has different box sizes - that will definitely help in the future....THANK YOU AGAIN!