There is already one big DX 10 only title set for release next year: the PC version of Halo 2. Then again this is from MS owned Bungie, so that isn't too surprising. Depending on how fast Vista is adopted will mean how soon more DX10 only titles are released. I don't think anyone right now can make the call about how fast Vista will spread on PC's. It is a given that most new computer purchases from major manufacturers will have Vista pre-installed once it is formally released. Beyond that is purely variable. While developers do seem genuinely pleased the improvements in DX 10, most of them are not abandoning DX 9 because of this. Open GL could certainly handle a geometry shader in Windows XP (or any other modern operating system for that matter) in theory. I haven't seen the three new nVidia extensions (EXT_gpu_shader4, EXT_geometry_shader4, and EXT_bindable_uniform) appear on SGI's Extension Registry. From the sound of it though, those extensions are available under Windows XP with Geforce 8800 cards and recent nVidia drivers. One thing worth noting is that Vista is playing catch up to OS X, Linux and modern UNIX systems a bit. Those operating systems have allowed for multiple applications to take advantage of 3D hardware for years.