Blurry images in shop "Replete theme"

Hello guys!

For a couple of weeks ago I purchased the “Replete business theme” and since then I had a lot of trouble with the images in my shop.

http://www.productme.se

It seems like the pictures are being increased to a ridiculous size in the shop, to like 1038 x 727, and then decreased on the “FrontPage” to show a preview of the products. There you can see how blurry they are. It is nothing wrong with the images that I ´ve uploaded and they are of a good quality as you can see below the huge image if you click on one of the products at the homepage.

I want it to look like something similar to this: http://docs.woothemes.com/wp-content/uploads/2012/01/adding-product-images-and-galleries-2.png

I´ve spent hours trying to figure it out and I have downloaded the “regenerate thumbnail” but nothing seems to work. I would love to not change any code since I want to be able to upgrade the theme without any problems. Can somebody please help me?

Regards, from Sweden.