IE is always taking resources, since it loads on startup.
People prefer it because of it's loading times, which is due to the statement above.
Mozilla has a quick launch option, which will start the browser with windows, in order to acheive a similiar effect.
Also, Mozilla's memory footprint goes down with each release, pretty much.
And really, I'm ok with using a few more MB of resources so I can use a slick browser that owns IE