Ever tried to play a modern computer game? You never have enough RAM for stuff; a lot of content gets dumped onto hard drive sooner or later (virtual memory), or is be streamed from the drive in the first place. Having faster access helps tremendously.<p>From my observation, actually most personal and business use machines are IO-bound - it often takes just the web browser itself - with webdevs pumping out sites filled with superfluous bullshit - to fill out your RAM completely, and then you have swapping back and forth.