I have been upgrading WP from 2.x.y and now I am running 3.3.1. Didn’t see any problems.
Try Athualpa Theme. I am using Atahualpa but my image is very much wider 1350×181. You can adjust the image height under Atahualpa Theme Options | Header Image: Height . You can see an example of Atahualpa theme at https://bachutha.com. There are plenty of thumbnails and my thumbnails are 300×300 pixels. I do not know whether you may have to fill in the sides of the image because your screen will be wider than your image. I had combined two or three pictures to make one large picture. The smaller 480×60 images on the right that look like advertisement, where added in the HTML under Atahualpa Theme Options|Overlay Header Image.
I love the Atahualpa theme because it allows me up to 4 sidebars – two on the left and two on the right and they can be of different width. You can see I am only using 2 sidebars – one on left and one on right. The right sidebar is broader than the left sidebar.
I hope this helps you
