No, I don’t think it would necessarily save a lot of battery life. It really depends on how efficient the OS, the drivers, and the software is. For instance, if coded properly, the DVD player would know to take advantage of all the special features of the CPU (SSE2, etc) and use the GPU to help accelerate the decoding (taking less strain off the CPU) and properly use the memory to cache portions of the DVD so that it doesn’t have to spin constantly. I don’t know how mature Linux DVD solutions are but Windows based ones are very fine-tuned. They cache the DVD, the codecs are tuned for battery/performance, they use hardware very efficiently, and are very mature.
Of course, I don’t know. I have never used a notebook that has these features so I can’t say 100% that it’s better or worse. From a technical standpoint, I don’t see that you could save a noticeable amount of battery.
