I was actually talking about the needed processing power to play back a Divx movie file compared to a DVD file. DVDs are MPEG2 and require less processing power to decode then Divx (basicially MPEG4). For example, the Farscape miniseries I am watching now takes 5-15% of the CPU to play back. It's an MPEG2 file off my ReplayTV. A Divx file I have from a DVD takes 15-30% of the CPU. Not a huge increase, but on a slower processor the difference will be more noticeable. It all depends on the system for how much power will be lost to decode compared to spinning a DVD. Modern laptops normally are able to downclock the CPU, and system bus to save power and quickly change depending on what the user does.