Disabling IE is good for security, I don't know if IE is still as terrible as it used to be, I hear it's great now, but I'll still never go back to it. Either way not here to bash IE, if you don't use it, remove it, gets rid of loose ends. Removing IE does not affect Steam or any other programs on the computer. On fresh installs of Windows since Windows XP I've disabled it and not once have I gotten an error or request to re-enable it. Still not here to bash IE, but because of how bad it used to be most programs do not rely on it, thus I've never heard of it being needed for something, but if it ever is needed all you have to do is re-check it and Windows will reinstall it, no DVD or downloading needed, takes just a minute.