Corey addresses a common problem with 3D internal constraints in Photoshop CS5 Extended.
There are a number of new features in this version making it worthwhile: Edge Detection, Content-Aware Fill, Puppet Warp, 64-bit for Macintosh, enhanced 3D features (Extended only), painting and brush enhancements, enhanced HDR, auto Lens Correction, Mini Bridge, and numerous other small enhancements.