problem, images not scaling in internet explorer 7 or less

My site works fine on all browsers except Internet Explorer 7 and lower. No surprise there.

My problem lies in the fact that when I upload images, i scale them down using the in built function in wordpress, which Firefox and Chrome and safari read fine.
When the page is open in Internet Explorer, the div class is the correct size, but it shows a full sized version of the image instead of a scaled down version.

Example image HERE!

I’ve tried adding the following max width code to my style.css which scales the images correctly in firefox etc, but changes notinh in IE.

max-width: 553px;
		width: expression(this.width > 553 ? 553: true);
		height: auto;

Can anyone help me, as I’ve searched and searched for help, and can’t get it to work. Very frustrating.
And help will be greatly appreciated.

My site is appreciateperspective.co.uk if you want to see what I mean.