I have to agree with Edfilho on this one. They would be nice as wallpapers, but they're going to look pretty bad in print. Here's a short list of issues:
- The raised text has to go. The problem is that you don't want to use raised text in print unless you're intending to print on a sheet with raised areas. Otherwise the 3D effect falls apart and ends up looking amatuerish.
- There is no clear front or back on these. The front should be used for attractive artwork, while the back should be used to convey information on the product. Useful information such as system requirements, disc-type labels, ratings, and copyrights add to the professional feel.
- The spine should always show the title in some form or another. This is so the customer can easily find the disk on a shelf. Other information such as "video disk" or "PC CDROM" makes for a nice addition, but is not required.
- Try to use all the available space (minus the necessary margins) with text and images. If your text doesn't take up enough space, then stretching it can make your layout look better. Note that stretching text is usually a professional layout package feature, but a reasonable approximation can be had in GIMP by stretching the text layer.
Below is a small version of DVD cover I was working on for Privateer Remake. Notice how the front and back are separated, and how the title is on the spine. The text is also stretched to fill all areas. Another good DVD cover I've seen recently was the one on the Unknown Enemy site. You might want to check it out for some inspiration.