IS will create better pictures because.. the lenses above are fairly 'slow', which means you'll need a steady hand in anything other than daylight.. the image stabilisation helps this somewhat, kinda saving you the need to buy a 'fast' lens (eg, a f/2.8 or bigger).. Personally i'd get something like a Sigma/Tamron 70-200 f/2.8 (about £400-500 from China) as it'd most likely cover most things you're likely to do (with your kit lens too).