Help with images and aspect ratio in wordpress?

Hi folks,

I have a site that uses a large amount of images from various sources. The images are all of a different size and when i import them into the media library they are displayed on my site in two different places, one as a small image (212x216px), and one at a larger size (465x474px). These two areas are in proportion but the problem is the images being imported all have a different aspect ratio and so some look out of proportion when on view. Is there a way to easily display these images in these two locations so they maintain their proportions?

I read somewhere about the resize class in css but have yet to give it a try as i thought you guys would be best to ask. Any help is much appreciated.