I know with Quake series (1,2,3 dunno about 4) made it possiable to install using a CD from a different OS. You would download the newest version of the runtime binaries, then just copy over the data files. However, so far I have not been able to do this. I have been trying for an hour to install Doom 3 using my PC CD. (I am not going to spend the money again to install it on a Mac, and no ... its not currently installed on any PCs) Any ideas ?