Quality of Scaled Images

I have noticed a difference in the quality of scaled images recently while working on a new website.
There are times when I need to include images from an external source or want to have all the images sized the same. I use the max-width and max-height CSS properties to accomplish this. Generally, manually resized thumbnails have better quality. However, this technique works quite well if you are starting with a sufficiently large enough source image (or using a decent browser) and it is a huge time saver.

I have been testing the website in different browsers to try and eliminate display issues in the layout. The interesting thing is that the image quality is much higher in Firefox as compared to Internet Explorer 7. If you have IE7 on your computer,  you can see what I mean for yourself:

Coupons Dealuxe
All of the scaled images for products that are listed look very smooth in Firefox. However, in Internet Explorer, the images have jagged edges and do not have smooth gradients in the colors. This becomes very apparent in images that have diagonal lines with high contrast.
In fact, all of the other major browsers besides Internet Explorer sport high quality scaled images. IE needs to DIE, for a long list of reasons :D