Have you thought of editing you theme so that the disc icon inside the case is the one from the game instead of just a generic static disc image?
EDIT: Unfortunately, it seems any theme that displays the cover image at anything other than straight on, (45, 15 degrees, etc) warps the image in some form or another.
@JNBAK: Is there no way to remedy this? Is this just a side affect caused by the way OPL tries to render the cover art? Are the OPL devs aware of this?