I love the idea of super hi-res textures, even though my current machine couldn't handle them. As more people upgrade their systems, they will be useable by a larger audience. Clearly, at that filesize, downloads are going to be a problem unless you have a high bandwidth connection. Make two versions, 4000x4000 and a 6000x6000 or whatever and make the latter "Pro" version available on CD as well as by download.

"Democracy is a pathetic belief in the collective wisdom of individual ignorance." - H. L. Mencken