Well, I dont really see how stuff coming on 2 CD's increases speed THAT much. I can see having 1 Install disk & 1 Play disk working but thats more a convenience thing rather than a speed thing.
One of the reasons that DVD software has not taken off is that there is a natural limit as to how much code a single group can churn out before the overheads from mangement get too high. Its very hard to pump out multi-million lines of code and its also very expensive. What else are you going to fill a CD?DVD with. With games, theres always textures/sounds/movies etc but a program really only needs code, a couple of pictures and some documentation. Putting in an hour of high quality movie into an office app is expensive and not going to be that huge a selling point. I suppose at some point, all the help files etc will be in movie format but, until then, it is still pretty much impossible to get a single app package to get much more than 600MB