Strange image quality problem?

For the passed few weeks that I have been working on our sites, sometimes we noticed that the image colors have been really off. We thought it had to do with when we sent them through gmail or something. We are still unclear as to what is doing this. I took a screen shot of an example which is really confusing to me, perhaps someone can please explain to me what might be causing this.

http://imgur.com/wDbzG.png

This is why I am so confused. If you look at the screenshot, you can see the image on the left is the one on the actual site when I click on the _MED to open the _LRG. The colors are how we want them. But when I look at the actual image that I uploaded to the site, it is very dull (on the right). Some of them are duller on the site then on my sources, and others like this are perfect on the site but the source is dull. I dont understand. Can anyone explain this, and also provide a tutorial on how to properly handle images to keep this color but reduce the file sizes?

Thanks.

Browsers only render images at 72dpi
I am not sure what picassa viewer renders at

From a large file size, Any extra info is discarded indiscriminantly

Hmm, well that confuses me even more, since the web images are the ones that are looking good. My local images are looking dull and bland. Could this have anything to do with like sRBG and apple1998 stuff? I really dont know much about it but I'm seeing stuff on google referring to it. Thanks.

Use something other picassa viewer locally

That is not the problem. Does anyone else have any experience with the color profiles between MAC's/PC's and how to save them for the web appropriately?

So we think we may have found some of the issue. Some of our images were in CMYK mode, so they were not saving in sRGB. So I went back to my .psd files and changed the mode to RGB, then saved them as jpeg and now they properly say sRGB in the details.

However, can someone please take a look at what I'm seeing now.

bullardpublishing

This link takes you directly to a product list, if you look at the very bottom image "Defending his harem" you will see that the thumb nail picture is nicely saturated in the trees, but now click on that item and the _MED & _LRG are showing as dull. Now I dont understand why the thumbnails are showing like that and the rest arent? Can anyone explain or help me? All of these images are now sRGB, confirmed with this tool : http://regex.info/exif.cgi

Thanks.