If L. S. made the game to run from the DVD with minimal registration file and HD usage it shall be an unprecedented product, and that might double its sales.
If you're interested, go check out the sales for Metal Gear Solid 2: Substance on PC. The 2nd week after the game was out, the price dropped by half.
Still, each time I walk in the stores, I still see the 4 copies of the game, untouched. Why? Because it is on DVD. The surest way to worsen <img src="/ubbthreads/images/graemlins/riftrunner.gif" alt="" />'s sales, is to publish a DVD. Most people won't upgrade their computers because of one game, so don't expect people buy a DVD-player with RiftRunner.