I found that your scrolling div just had a black background, no image, so I added my own background-image.
This explains the general situation:-
http://www.quirksmode.org/css/background.html
Even so, I couldn't get IE7 to fix the background-image. background-attachment: fixed just made the image disappear because it was then related to the whole screen, not to div, as explained in the link above.
The only way I could get IE7 to fix the background-image was to repeat the image and also fix it with this code:-
<div class="style1" id="text" style="width: 436px;
height: 357px; overflow: auto; padding-left: 10px; padding-right:
4px; background-image: url(images/txt_bkgrnd.jpg);
background-repeat: repeat; background-attachment:
fixed;">
<!--was background-repeat: no-repeat; background-position:
top, left; background-attachment: scroll;-->
Since I used my own image and it repeated but stayed fixed I'm not sure if it works with your image as I couldn't download txt_bkgrnd.jpg.
Also the background-position: top, left; should be background-position: top left; without the , but this wasn't the problem as top left is the default so the error didn't matter.
Code downloaded to my PC will be deleted in due course.
WIN7; IE9, Firefox, Opera, Chrome and Safari for Windows; screen resolution usually 1366*768.
Also IE6 on W98 with 800*600 and IE8 on Vista 1440*900.