HI welcome to Sitepoint 
Kylle’s solution above should work but the cause of the problem is the text-align:center on the body. Just remove text-align:center and it will work in IE7+.
The reason is that when you place an absolute element without using co-ordinates then IE also takes into account the text alignment and if it is not text-align:left the absolute element is then offset by that text alignment. Using co-ordinates forces the issue but sometimes you don’t want co-ordinates as you want the element to move in its current context so just make sure that text-align:left is set on a parent of the fixed/absolute element.
There are a few things that need tidying up
You have corrupt conditional comments as there needs to be a space before the 8 in “lte IE 8” so luckily the styles were ignored as none of those rules are in fact needed. You should only have the extra rules in the IE stylesheet and not a whole stylesheet again. Your page doesn’t actually need any help for IE7 plus so you only need to include rules for IE6 if you want to support it.
You have also included the style tag in the css file which is not allowed as the style tag is an html element and only belongs in the html. Just add css and css comments to the css file - nothing else.
Your page is lacking a bit in structure as you have no H1 (the most important element on the page) and you are using breaks to make space which is not their job. Use css to make space with padding/margins on existing elements.
Headings should also be in logical order and you can’t jump straight to an h5 from an h2:
<h2 id="previewparty">Gala Preview Party</h2>
<h5>the Joseph & Robert Cornell Memorial Foundation,<br/>
Gala and Signature Sponsor</h5>
<h3>Friday, March 23rd, 6:00 to 9:00 PM <br/>
Main Street Arena, on the Mall across from the Omni</h3>
<h4>Tickets by Reservation Only and Limited: $55 /$100 per couple</h4>
It should run h2 - h5 or h2 h3, h2, h3 h4 etc… Also make sure that they really are headings identifying sub sections and not just because you want bold text etc.
You also have a lot of empty divs where you have applied background images ans that is ok if they are just decoration but be careful if they are important to content as screenreaders and search engines will see no content. Use an image replacement technique id they are important content or use the actual image in the html. If the images are just wallpaper then it doesn’t matter and can stay ion the background.
Lastly that footer image is nearly 800k and probably ten times the size of my maximum. Do you really want it that big and obscuring the whole screen?. Mobile users will get the image and nothing else I would imagine.